Source : Webster's Revised Unabridged Dictionary (1913)

Crustaceous \Crus*ta"ceous\ (kr?s-t?"sh?s; 97), a. [NL.
   crustaceous. See {crustacea}.]
   1. Pertaining to, or of the nature of, crust or shell; having
      a crustlike shell.

   2. (Zo["o]l.) Belonging to the Crustacea; crustacean.

Source : WordNet®

crustaceous
     adj 1: of or belonging to the class Crustacea [syn: {crustacean}]
     2: being or having or resembling a hard crust or shell