Pronunciation: (thôr"u-kos'tu-mē, thōr"-), [key]
—pl. -mies. Surg.
1. the construction of an artificial opening through the chest wall, usually for the drainage of fluid or the release of an abnormal accumulation of air.
2. the opening so constructed.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.