What does endorse mean?

Question

According to Oxford Languages,

sign (a check or bill of exchange) on the back to make it payable to someone other than the stated payee or to accept responsibility for paying it.

I'm having trouble understanding the bolded part. "sign (a check or bill of exchange) on the back to make it payable to someone other than the stated payee" is clear. This basically means that if my father is the stated payee on the cheque, and he endorses the cheque using my name, then I will be able to encash the cheque as well. However, what does "to accept responsibility for paying it" mean?

Answer 1

It means if the check bounces, you still have to pay

A check is a negotiable instrument which means it can be passed from hand to hand as a promise to pay before eventually being converted to cash.

However, if I hold the check from you but it’s originally from someone else, you are promising to pay me irrespective of if the original drawer makes good on their promise to pay you.

Answer 2

One kind of negotiable instrument which illustrates the point most familiarly is a negotiable promissory note.

If you sign a promissory note even if the loan is made to someone else, i.e. if you endorse the promissory note, by doing so, you accept responsibility for paying it.

The language in the sentence breaks out:

sign (a check or bill of exchange) on the back

[a] to make it payable to someone other than the stated payee or

[b] to accept responsibility for paying it.

There are two different purposes for which you could endorse the instrument. One is the change the payee and another is to change the payor.

The language is somewhat awkward, because usually when you sign to accept responsibility for paying it, you sign on the front and not the back.

For example, if your bank "certifies" your personal check, it is basically co-signing the promise to pay the payee that you made by signing the check.