Definition of penknifes:
(n) :
A small pocketknife; (loosely) any pocketknife.
(n) :
(dated) A small knife designed for safe and convenient storage, typically in the form of a miniature clasp-knife, or with blade retractable into the handle.
(v) :
(transitive) To cut or carve with a penknife.
(n) :
(archaic) A small knife for cutting the points of quill feathers or reeds into nibs to provide or repair writing implements, early versions were commonly small sheath knives.