TREPANn.
[L. tero, terebra, on the root Rp.] In surgery, a circular saw for perforating the skull. It resembles a wimble.
TREPANv.t.
To perforate the skull and take out a piece; a surgical operation for relieving the brain from pressure or irritation.
Trepan, a snare, and trepan, to ensnare, are from trap, and written trepan, which see.