1) a comrade, mate, partner
2) in kindly address
2a) friend, (my good friend)
Part of Speech: noun masculine
Citing in TDNT: 2:699, 265
From ἔτης etês (a clansman); a comrade: - fellow, friend.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἑταῖρος; click on the second column to search for that grammatical form of the root ἑταῖρος; click on the third column to search for that word and grammatical form; click on the total to search for the root ἑταῖρος.