Say that a person were coerced into performing indecent acts of a sexual nature, such as nudity, masturbation, oral sex, etc. If intercourse occurs, that would be classified as "rape". What would the legal term be for these other coerced acts?
There is not a single legal term that encompasses all of these offenses in most jurisdictions. Instead, there are a number of different offenses that could apply based upon whether or not there is sexual contact, the nature of the coercion involved, and certain other details of the offense.
To use a concrete and precise example, I provide the exact language of the most relevant offenses in Colorado's criminal statutes, since they are easily available to me and I am familiar with them, and they are typical, for the most part. I omit the language used to determine offense category within offenses when there are more and less aggravated versions of an offense that have different criminal penalties (e.g. kidnapping has a higher grade of offense if it is not possible to verify that the kidnapped victim has been subsequently released and is alive).
But, the terminology used for the kinds of offenses that you describe in not nearly so uniform as the terminology used for sexual assault or rape (and some jurisdictions would include some or all of the conduct you describe as a subtype of sexual assault).
In Colorado, there is an offense called "Unlawful sexual contact". Section 18-3-404, Colorado Revised Statutes, which basically means a rape that does not involve penetration.
Any actor who knowingly subjects a victim to any sexual contact commits unlawful sexual contact if:
(a) The actor knows that the victim does not consent; or
(b) The actor knows that the victim is incapable of appraising the nature of the victim's conduct; or
(c) The victim is physically helpless and the actor knows that the victim is physically helpless and the victim has not consented; or
(d) The actor has substantially impaired the victim's power to appraise or control the victim's conduct by employing, without the victim's consent, any drug, intoxicant, or other means for the purpose of causing submission; or
(f) The victim is in custody of law or detained in a hospital or other institution and the actor has supervisory or disciplinary authority over the victim and uses this position of authority, unless incident to a lawful search, to coerce the victim to submit; or
(g) The actor engages in treatment or examination of a victim for other than bona fide medical purposes or in a manner substantially inconsistent with reasonable medical practices.
There is also an offense called "Invasion of privacy for sexual gratification". Section 18-3-405.6, Colorado Revised Statutes (same link).
A person who knowingly observes or takes a photograph of another person's intimate parts without that person's consent, in a situation where the person observed or photographed has a reasonable expectation of privacy, for the purpose of the observer's own sexual gratification, commits unlawful invasion of privacy for sexual gratification.
It is generally used for peeping tom type offenses, but could conceivable involve forcing someone to expose themselves sexually without their consent but without physical contact with the offender.
Similarly, "Internet sexual exploitation of a child", might apply to some cases, and is defined at Section 18-3-405.4, Colorado Revised Statutes (same link), although "importunes" and "entices" isn't really the same as coercion, and is instead more in the nature of deception than than coercion.
An actor commits internet sexual exploitation of a child if the actor knowingly importunes, invites, or entices through communication via a computer network or system, telephone network, or data network or by a text message or instant message, a person whom the actor knows or believes to be under fifteen years of age and at least four years younger than the actor, to:
(a) Expose or touch the person's own or another person's intimate parts while communicating with the actor via a computer network or system, telephone network, or data network or by a text message or instant message; or
(b) Observe the actor's intimate parts via a computer network or system, telephone network, or data network or by a text message or instant message.
In contrast, "Sexual assault" (a.k.a. "rape") is defined at Section 18-3-402, Colorado Revised Statutes (same link) as:
Any actor who knowingly inflicts sexual intrusion or sexual penetration on a victim commits sexual assault if:
(a) The actor causes submission of the victim by means of sufficient consequence reasonably calculated to cause submission against the victim's will; or
(b) The actor knows that the victim is incapable of appraising the nature of the victim's conduct; or
(c) The actor knows that the victim submits erroneously, believing the actor to be the victim's spouse; or
(d) At the time of the commission of the act, the victim is less than fifteen years of age and the actor is at least four years older than the victim and is not the spouse of the victim; or
(e) At the time of the commission of the act, the victim is at least fifteen years of age but less than seventeen years of age and the actor is at least ten years older than the victim and is not the spouse of the victim; or
(f) The victim is in custody of law or detained in a hospital or other institution and the actor has supervisory or disciplinary authority over the victim and uses this position of authority to coerce the victim to submit, unless the act is incident to a lawful search; or
(g) The actor, while purporting to offer a medical service, engages in treatment or examination of a victim for other than a bona fide medical purpose or in a manner substantially inconsistent with reasonable medical practices; or
(h) The victim is physically helpless and the actor knows the victim is physically helpless and the victim has not consented.
Colorado does not have a provision parallel to statutory rape for unlawful sexual contact, nor does it have a deception to make someone think that a partner is a spouse provision for unlawful sexual contact, even though that is a recognized form of sexual assault.
These are clarified with definitions in Section 18-3-401, Colorado Revised Statutes (same link; definitions inapplicable to the offenses cited omitted):
(1) "Actor" means the person accused of a sexual offense pursuant to this part 4.
(1.5) "Consent" means cooperation in act or attitude pursuant to an exercise of free will and with knowledge of the nature of the act. A current or previous relationship shall not be sufficient to constitute consent under the provisions of this part 4. Submission under the influence of fear shall not constitute consent. Nothing in this definition shall be construed to affect the admissibility of evidence or the burden of proof in regard to the issue of consent under this part 4. . . .
(2) "Intimate parts" means the external genitalia or the perineum or the anus or the buttocks or the pubes or the breast of any person. . . .
(3) "Physically helpless" means unconscious, asleep, or otherwise unable to indicate willingness to act. . .
(4) "Sexual contact" means the knowing touching of the victim's intimate parts by the actor, or of the actor's intimate parts by the victim, or the knowing touching of the clothing covering the immediate area of the victim's or actor's intimate parts if that sexual contact is for the purposes of sexual arousal, gratification, or abuse.
(5) "Sexual intrusion" means any intrusion, however slight, by any object or any part of a person's body, except the mouth, tongue, or penis, into the genital or anal opening of another person's body if that sexual intrusion can reasonably be construed as being for the purposes of sexual arousal, gratification, or abuse.
(6) "Sexual penetration" means sexual intercourse, cunnilingus, fellatio, analingus, or anal intercourse. Emission need not be proved as an element of any sexual penetration. Any penetration, however slight, is sufficient to complete the crime.
(7) "Victim" means the person alleging to have been subjected to a criminal sexual assault.
Also closely related is "criminal invasion of privacy", Section 18-7-801, Colorado Revised Statutes (at the same link), which is primarily targeted at "up skirt" photos, but could be used for the kind of offense described in the question.
(1) A person who knowingly observes or takes a photograph of another person's intimate parts, as defined in section 18-3-401 (2), without that person's consent, in a situation where the person observed or photographed has a reasonable expectation of privacy, commits criminal invasion of privacy. . . .
(3) For the purposes of this section, "photograph" includes a photograph, motion picture, videotape, live feed, print, negative, slide, or other mechanically, electronically, digitally, or chemically reproduced visual material.
There is also offenses called "Human trafficking for sexual servitude" and "human trafficking of a minor for sexual servitude". Section 18-3-504, Colorado Revised Statutes (same link), which could sometimes apply (human trafficking without sexual servitude is also a crime but not within the scope of the question).
A person who knowingly sells, recruits, harbors, transports, transfers, isolates, entices, provides, receives, or obtains by any means another person for the purpose of coercing the person to engage in commercial sexual activity commits human trafficking for sexual servitude.
This is clarified with many definitions at Section 18-3-503, Colorado Revised Statutes (same link):
(1) "Adult" means a person eighteen years of age or older.
(2) "Coercing" means inducing a person to act or to refrain from acting, if the inducement is accomplished by any one or more of the following means:
(a) The use or threat of the use of force against, abduction of, causing of serious harm to, or physical restraint of a person;
(b) The use of a plan, pattern, or statement for the purpose of causing the person to believe that failure to perform the act or failure to refrain from performing the act will result in the use of force against, abduction of, causing of serious harm to, or physical restraint of that person or another person;
(c) Using or threatening to use the law or the legal process, whether administrative, civil, or criminal, in any manner or for any purpose for which the law was not designed;
(d) Threatening to notify law enforcement officials that a person is present in the United States in violation of federal immigration laws;
(e) The destruction or taking, or a threat to destroy or take, a person's identification document or other property;
(f) Controlling or threatening to control a person's access to a controlled substance, as defined in section 18-18-102 (5);
(g) The use of debt bondage; or
(h) The exploitation of a person's physical or mental impairment, where such impairment has a substantial adverse effect on the person's cognitive or volitional functions.
(3) "Commercial sexual activity" means sexual activity for which anything of value is given to, promised to, or received by a person.
(4) "Debt bondage" means:
(a) Demanding commercial sexual activity as payment toward or satisfaction of a real or purported debt; or
(b) Demanding labor or services as payment toward or satisfaction of a real or purported debt and failing to apply the reasonable value of the labor or services toward the liquidation of the debt; or
(c) Demanding labor or services where the length of the labor or services is not limited and the nature of the labor or services is not defined.
(5) "Identification document" means a real or purported passport, driver's license, immigration document, travel document, or other government-issued identification document, including a document issued by a foreign government.
(6) "Maintain" means to provide sustenance or care for a minor and includes but is not limited to providing shelter, food, clothing, drugs, medical care, or communication services.
(7) "Makes available" means to facilitate contact between a minor and another person.
(8) "Minor" means a person less than eighteen years of age.
(9) "Person" has the same meaning as set forth in section 2-4-401 (8), C.R.S.
(10) "Serious harm" means bodily injury or another harm, whether physical or nonphysical, including psychological, financial, or reputational harm, which is sufficiently serious, under all the surrounding circumstances, to compel a reasonable person to perform or continue to perform labor or services or sexual activity to avoid incurring the harm.
(11) "Sexual activity" means:
(a) Sexual contact, as defined in section 18-3-401 (4);
(b) Sexual intrusion, as defined in section 18-3-401 (5);
(c) Sexual penetration, as defined in section 18-3-401 (6);
(d) Sexual exploitation of a child, pursuant to section 18-6-403 (3) (a) and (3) (d); or
(e) An obscene performance, as defined in section 18-7-101.
(12) "Victim" means a person who is alleged to have been, or who has been, subjected to human trafficking, as described in section 18-3-503 or section 18-3-504.
An obscene performance, referenced above is defined at Section 18-7-101, Colorado Revised Statutes (same link) in the pertinent parts, to mean:
(2) "Obscene" means material or a performance that:
(a) The average person, applying contemporary community standards, would find that taken as a whole appeals to the prurient interest in sex;
(b) Depicts or describes:
(I) Patently offensive representations or descriptions of ultimate sex acts, normal or perverted, actual or simulated, including sexual intercourse, sodomy, and sexual bestiality; or
(II) Patently offensive representations or descriptions of masturbation, excretory functions, sadism, masochism, lewd exhibition of the genitals, the male or female genitals in a state of sexual stimulation or arousal, or covered male genitals in a discernibly turgid state; and
(c) Taken as a whole, lacks serious literary, artistic, political, or scientific value. . . .
(4) "Patently offensive" means so offensive on its face as to affront current community standards of tolerance.
(5) "Performance" means a play, motion picture, dance, or other exhibition performed before an audience. . . .
(6.5) "Prurient interest" means a shameful or morbid interest.
A person, as defined in the referenced language is defined as follows:
"Person" means any individual, corporation, government or governmental subdivision or agency, business trust, estate, trust, limited liability company, partnership, association, or other legal entity.
Sometimes false imprisonment or kidnapping would be relevant charges:
"First degree kidnapping" is Section 18-3-301, Colorado Revised Statutes (at the same link) would apply when someone else is kidnapped for purposes of coercing the person made to conduct the sexual act:
Any person who does any of the following acts with the intent thereby to force the victim or any other person to make any concession or give up anything of value in order to secure a release of a person under the offender's actual or apparent control commits first degree kidnapping:
(a) Forcibly seizes and carries any person from one place to another; or
(b) Entices or persuades any person to go from one place to another; or
(c) Imprisons or forcibly secretes any person.
Sometimes the victim would also be a victim of "second degree kidnapping" per Section 18-3-302, Colorado Revised Statutes (at the same link):
(1) Any person who knowingly seizes and carries any person from one place to another, without his consent and without lawful justification, commits second degree kidnapping.
(2) Any person who takes, entices, or decoys away any child not his own under the age of eighteen years with intent to keep or conceal the child from his parent or guardian or with intent to sell, trade, or barter such child for consideration commits second degree kidnapping.
One can also imagine this offense including "false imprisonment", Section 18-3-303, Colorado Revised Statutes (same link):
Any person who knowingly confines or detains another without the other's consent and without proper legal authority commits false imprisonment. This section shall not apply to a peace officer acting in good faith within the scope of his or her duties.
"Criminal extortion" (a.k.a. "blackmail") defined at Section 18-3-207, Colorado Revised Statutes (at the same link) is likewise a plausible offense depending upon the nature of the coercion:
(1) A person commits criminal extortion if:
(a) The person, without legal authority and with the intent to induce another person against that other person's will to perform an act or to refrain from performing a lawful act, makes a substantial threat to confine or restrain, cause economic hardship or bodily injury to, or damage the property or reputation of, the threatened person or another person; and
(b) The person threatens to cause the results described in paragraph (a) of this subsection (1) by:
(I) Performing or causing an unlawful act to be performed; or
(II) Invoking action by a third party, including but not limited to, the state or any of its political subdivisions, whose interests are not substantially related to the interests pursued by the person making the threat.
(1.5) A person commits criminal extortion if the person, with the intent to induce another person against that other person's will to give the person money or another item of value, threatens to report to law enforcement officials the immigration status of the threatened person or another person.
If drugs are used to induce the sexual conduct, assault charges could apply. The relevant offense in Colorado is "second degree assault", Section 18-3-203(1)(e), Colorado Revised Statutes (at the same link):
A person commits the crime of assault in the second degree if: . . . (e) For a purpose other than lawful medical or therapeutic treatment, he intentionally causes stupor, unconsciousness, or other physical or mental impairment or injury to another person by administering to him, without his consent, a drug, substance, or preparation capable of producing the intended harm;
Notably, in Colorado, unlike many states and countries, intentionally causing bodily injury that is not serious bodily injury and does not involve a deadly weapon or a first responder injury, is a tort or municipal ordinance violation, but not a state law crime, except for some subtypes of disorderly conduct, harassment and hazing.
"Disorderly conduct" includes assault in the context of fighting in public, in Colorado, but wouldn't be applicable in the circumstances of the question. Section 18-9-106, Colorado Revised Statutes (same link).
A person commits disorderly conduct if he or she intentionally, knowingly, or recklessly: . . . (d) Fights with another in a public place except in an amateur or professional contest of athletic skill
"Harassment" is closest to bare physical assault in Colorado, and could apply in some of these cases. Section 18-9-111, Colorado Revised Statutes (same link).
A person commits harassment if, with intent to harass, annoy, or alarm another person, he or she: (a) Strikes, shoves, kicks, or otherwise touches a person or subjects him to physical contact
"Hazing" is defined in Section 18-9-124, Colorado Revised Statutes, and could be implicated if the means of coercion are related to this kind of activity.
(2) As used in this section, unless the context otherwise requires:
(a) "Hazing" means any activity by which a person recklessly endangers the health or safety of or causes a risk of bodily injury to an individual for purposes of initiation or admission into or affiliation with any student organization; except that "hazing" does not include customary athletic events or other similar contests or competitions, or authorized training activities conducted by members of the armed forces of the state of Colorado or the United States.
(b) "Hazing" includes but is not limited to:
(I) Forced and prolonged physical activity;
(II) Forced consumption of any food, beverage, medication or controlled substance, whether or not prescribed, in excess of the usual amounts for human consumption or forced consumption of any substance not generally intended for human consumption;
(III) Prolonged deprivation of sleep, food, or drink.
(3) It shall be unlawful for any person to engage in hazing.
If the conduct causes serious bodily injury or the loss of a pregnancy, there are other charges that could apply.
There are also offenses that might apply in certain situations that apply only to certain kinds of victims or certain kinds of relationships.
For example offenses limited to minors like child abuse, domestic violence offenses, offenses related to abuse of "at risk" persons, offenses related to sexual offenses involving psychotherapists, sexual offenses involving abuse of a position of trust, solicitation of prostitution, child prostitution offenses, criminal conspiracy charges, criminal solicitation charges, criminal attempt charges, organized crime charges when there is a pattern of such conduct for profit by an organization or group of people, etc.
It's probably going to vary by jurisdiction, but I think England and Wales would treat it as "Sexual Assault".
There's also the option of prosecuting the coercion itself (independent of what act the victim is forced to do), which might come under "blackmail" with the sexual nature an aggravating feature when sentencing. On the other hand it might not get beyond "assault" which has quite a low maximum sentence.