This definition is here only for the sake of those who are surfing the Web and stumbled onto this page. Those of you already doing CI may as well go back. I've never seen a definition of Contact that I really liked. For some people, it's a post-modern folk dance. For others, it's a process for finding new choreographic ideas.
Some people perform it, others do it as a practise or discipline.
Some people look at it and see gymnastics, or wrestling, or swing dance. Dancers are as likely to be on the floor as standing, and sometimes they're flying on someone else's shoulders. You might want to see the photographs and videos for some examples. The single best place to find out more, short of just doing it, is in the pages of Contact Quarterly , a magazine that covers contact and the extended family of new dance. See also the bibliography of contact improvisation collected at CI25.