- 1) together: used with some nouns, verbs, and adjectives
coeducation (= the education of boys and girls together)
cohabiting couples (= people living together without being married)2) sharing a job or responsibility: used with some nouns, verbs, and adjectives
her co-star (= another main actor taking part with her in the film)
my co-driver (= someone who drives so that I can rest)
English dictionary. 2014.