co- /kəʊ $ koʊ/ BrE AmE prefix
[ Language: Latin ; Origin: 'together, with' , from com- ; ⇨ COM- ]
1 . together with:
to coexist (=exist together or at the same time)
coeducation (=with boys and girls together)
2 . doing something with someone else as an equal or with less responsibility:
my co-author (=someone who wrote the book with me)
the co-pilot (=someone who helps a pilot)