What is a colonic?

Pertaining to colon: However, many people use it as a noun and mean a colonic enema. There are a number of so called "health treatments" that in involve high colonic enemas, or so called "clean outs". Efficacy of these "high colonics" is scientifically unproven & suspect. Colonic enemas may be required for some subjects with severe constipation, neurogenic bowel dysfunction or as part of pre-operative bowel prep.