Problem
A colleague is designing an application and wants to decide what to write in the return/enter key.
Research
In the Macbook keyboard both terms are present (return and enter).
Question
My question is: which term is the most used US English word for such operation?
Best Answer
You question suggests that you are unaware that the ‘return’ and ‘enter’ keys are not necessarily one and the same, although they are on the Mac keyboard you show. It is not a question of US English v. British English (we Brits don’t make computers any more) but more of your audience: Mac v PC, or whether you are describing a specific effect to a technical audience. You can read about it in this Wikipedia article, and make your own decision.
That said, it would appear from googling that ‘Enter’ is most common, as it is apparently the preferred PC/Windows usage (I wouldn’t know from personal experience as I’m also a Mac user), and as your Mac keyboard has both terms (my laptop has neither) I’d suggest you use that (perhaps with ‘Return’ in parentheses if style allows).