clavis

noun4

1. •
   A Roman key.

   • Iron clavis, the solid web-shaped at the edges to fit the wards in the lock, and having a pointed broach and a kite-formed looped haft. — 1873
2. •
   A key; an identification guide; a series of logically organized groups of discriminating information which aims to allow the user to correctly identify a taxon.
3. •
   Synonym of glossary: a key to the meaning of various terms.

   • Homer, with a clavis, I have had possession of some years. — 1784
4. •
   A device for restraint of the hands.

   • His hands were restrained by means of a clavis and bolt (of iron), appropriated to each wrist, and united by a padlock. — 1904