Here is the context:
Please enter a colleagues email address:
My coworker believes that in this context, it should be colleagues. I think that because it is a possessive noun, that it should be colleague's. I am no English expert, but I did learn about the use of apostrophes in public school... which version is correct?
You are correct, it should be colleague's, as it is their email address you are asked to enter.
Another way to phrase this would be Please enter the email address of a colleague; here the possessive is expressed through the of.
What do you want to indicate? Colleague in singular form, or to state that someone has a colleague?
Singular form:
"Please enter a colleague email address"
Possession form:
"Please enter a colleague's email address"
Plural form:
"Please enter your colleagues email addresses" (attention to the plural on address in this case).
