Whilst the origin of the two words is different, both trepan and trephine have become synonymous as have the nouns trepanation and trephination and the verbs trepanning and trephining.

Castellated Crown Drills with Centre Pins

Craniotomy

(from cranium: skull; tomy: make an incision) means to make a hole in the head

Trepan

(from trupanon: Greek for borer) a boring instrument used commonly on the skull

Trephine

(originally from Tres-fines a drill with three handles or ends) (1) a crown saw for the removal of a disk of bone, especially from the skull.

• Next: Why Drill Holes in Heads?
• Previous: ABC: A History of Craniotomy