In English law, I'm struggling to find a consistent definition of "assault", or at least, a way to decide what definition to apply:
Sometimes it appears to mean "to intentionally or recklessly cause another person to apprehend immediate and unlawful personal violence". With this definition, an actual act of unlawful physical contact is a battery, which is something different to an assault. Alice threatening to punch Charlie is an assault, Bob punching Charlie is a battery.
Other times the word "assault" appears to be an umbrella term which self-referentially includes "assault" OR "battery". Using this definition, it doesn't matter whether there is physical contact: it can be referred to as an assault either way. Alice threatening to punch Charlie is an assault, Bob punching Charlie can be called an assault or a battery - both are correct terms.
The terms "assault" and "common assault" also seem to be interchangeable in some texts, or in other texts used to differentiate between the two possible meanings of assault (so e.g. a text might claim that "common assault" is sub-divided into "assault" and "battery"). I have even seen this explained the other way around, whereby "assault" is sub-divided into "common assault" and "battery", so even this use of the terms is not consistent.
The confusion is perpetuated by judges. For example, James J. in Fagan v Metropolitan Police Commissioner  1 QB 439 said:
An assault is any act which intentionally—or possibly recklessly—causes another person to apprehend immediate and unlawful personal violence. Although "assault" is an independent crime and is to be treated as such, for practical purposes today "assault" is generally synonymous with the term "battery" and is a term used to mean the actual intended use of unlawful force to another person without his consent. On the facts of the present case the "assault" alleged involved a "battery."
I'm not sure what to make of this. We are to "treat as such" that "assault" is an independent crime, but then it goes on to contradict this by saying that in the present case we can include the "battery" as being part of the "assault", because the two are "generally synonymous". It's hard to see how he can justify both positions simultaneously.
So, ignoring the every day English language meaning of the words, is there in fact a clear and precise definition of "assault" (in which case some sources are simply using it incorrectly), or do I just need to accept that there is confusion, even within the law itself, and rely on context to establish in any given instance which meaning is meant?