thoracotomy (n.)

"chest of the body," late 14c., from Latin thorax "the breast, chest; breastplate," from Greek thōrax (genitive thōrakos) "breastplate, chest," of unknown origin.

word-forming element meaning "surgical removal," from Latinized form of Greek -ektomia "a cutting out of," from ektemnein "to cut out," from ek "out" (see ex-) + temnein "to cut" (from PIE root *tem- "to cut").