co-

UK [kəʊ] / US [koʊ] prefix

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)