The Collaborative International Dictionary
Tusk \Tusk\, n. [OE. tusk, the same word as tusch, AS. tusc. See Tush a tooth.]
(Zo["o]l.) One of the elongated incisor or canine teeth of the wild boar, elephant, etc.; hence, any long, protruding tooth.
(Zo["o]l.) A toothshell, or Dentalium; -- called also tusk-shell.
(Carp.) A projecting member like a tenon, and serving the same or a similar purpose, but composed of several steps, or offsets. Thus, in the illustration, a is the tusk, and each of the several parts, or offsets, is called a tooth.