How is it correctly spelled?
closed as general reference by simchona♦ Dec 31 '12 at 7:58
This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information. If this question can be reworded to fit the rules in the help center, please edit the question.
Age mate or age-mate.
Age-mate seems to be the most popular, according to Ngram, and a bit of a 1970s thing.