If I want to describe something which I haven't done from a duration of time, then what should I use? Consider example:
I haven't met my friend since a year.
OR
I haven't met my friend for a year.
Learn English – Which is correct: ‘haven’t done since’ or ‘haven’t done for’
phrase-usage
Best Answer
When you are referring to duration, use “for” or “in”; when referring to the last time something happened, use “since”. “Since” will always require that you specify a point in time, not a span.
Your second option is grammatical and perhaps even ideal in BrE. For AmE, if you haven't rendezvoused, visited, or met up with your friend in a year, I recommend you say:
It all depends on exactly what you wish to convey, but some people may associate “meeting” with either the impossible-to-repeat act of making someone's acquaintance or the cold sense of business meetings.