noun a snare; a trapan.
2. trepan ·noun a deceiver; a cheat.
3. trepan ·noun a kind of broad chisel for sinking shafts.
4. trepan ·vt to insnare; to trap; to trapan.
5. trepan ·noun a crown-saw or cylindrical saw for perforating the skull, turned, when used, like a bit or gimlet. ·see trephine.
6. trepan ·vt & ·vi to perforate (the skull) with a trepan, so as to remove a portion of the bone, and thus relieve the brain from pressure or irritation; to perform an operation with the trepan.