trephine
noun
tre·phine ˈtrē-ˌfīn 
: a surgical instrument for cutting out circular sections (as of bone or corneal tissue)
trephine transitive verb
Word History
Etymology
French tréphine, from obsolete English trefine, trafine, from Latin tres fines three ends, from tres three + fines, plural of finis end — more at three
First Known Use
1628, in the meaning defined above
Medical Definition
trephine 1 of 2
noun
tre·phine ˈtrē-ˌfīn
: a surgical instrument for cutting out circular sections (as of bone or corneal tissue)
trephine
2 of 2transitive verb
tre·phine ˈtrē-ˌfīn tri-ˈ
tri-ˈ trephined; trephining
: to operate on with or extract by means of a trephine