Kumite (組手) means sparring, and is one of the three main sections of karate training, along with kata and kihon. Kumite is the part of karate in which a person trains against an adversary, using the techniques learned from the kihon and kata.
Kumite can be used to develop a particular technique or a skill (e.g. effectively judging and adjusting one's distance from one's opponent) or it can be done in competition.
Read more about Kumite: Gohon Kumite and Jiyu Kumite, Delivering Strikes, Competition, Popular Culture