trepanning

noun

1. an early form of the trephine
2. a heavy boring tool for sinking shafts, quarrying, etc.

Origin: ME trepane < ML trepanum < Gr trypanon, carpenters' tool, auger, trepan < trypan, to bore < IE *treup- < base *ter-, to bore, rub > throw

transitive verb trepanned, trepanning

1. trephine
2. to cut a disk out of (a metal plate, ingot, etc.)