penknife

Short definition from Wiktionary

Noun

1. 1
   A small pocketknife; (loosely) any pocketknife.
2. 2
   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.
3. 3
   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.

Verb

1. 1
   To cut or carve with a penknife.