Prefix: co, com, con,col (with or together)

committee

a group of people who meet together to discuss a topic

community

a place where people live together

coincidence

a sequence of events happening together that although accidental seems to have planned or arranged

compatible

able to live together and get along; things that can go together without problems, the roommates were compatible

co-ed (coeducational)

males and females going to school together, some colleges are not co-ed (Barnard, Simmons, Smith etc)

cohesive

sticking together

communication

the act of talking with someone and discussing something together

concur

to agree with another person's opinion

compare

to put things together to see how they are the same

combine

to put two things together

co-sign

to sign with another person (called a co-signer), if you are under 18 you need a co-signer, if you need a loan you will need a cosigner

coordinate

to work together or help people work together, also a term used in math on a graph

collide

when cars collide they bump into each other, cars come together-collision (noun)

commiserate

to feel sorry for someone, something, or a situation; students can commiserate about homework or a serious event

collect

to gather things together

coexist

to live together without any problems; to be together in the same time or place

conspire

to plan together secretly