colostomy (n.)

"large intestine," late 14c., from Latin colon, Latinized form of Greek kolon (with a short initial -o-) "large intestine," which is of unknown origin.

"orifice, small opening in an animal body," 1680s, Modern Latin, from Greek stoma (genitive stomatos) "mouth; mouthpiece; talk, voice; mouth of a river; any outlet or inlet," from PIE root *stom-en-, denoting various body parts and orifices (source also of Avestan staman- "mouth" (of a dog), Hittite shtamar "mouth," Middle Breton staffn "mouth, jawbone," Cornish stefenic "palate"). Surgical sense is attested from 1937.

"surgical operation making a permanent opening in the body," 1957, abstracted from colostomy, etc.; ultimately from Modern Latin stoma "opening, orifice," from Greek stoma "mouth" (see stoma).