The Collaborative International Dictionary of English v.0.48:

Crater \Cra"ter\ (kr[=a]"t[~e]r), n. [L. crater, cratera, a
   mixing vessel, the mouth of a volcano, Gr. krath`r, fr.
   keranny`nai to mix; cf. Skr. [,c]r[imac] to mix, [,c]ir to
   cook, [,c]r[=a] to cook. Cf. Grail, in Holy Grail.]
   1. The basinlike opening or mouth of a volcano, through which
      the chief eruption comes; similarly, the mouth of a
      geyser, about which a cone of silica is often built up.
      [1913 Webster]

   2. (Mil.) The pit left by the explosion of a bomb, shell, or
      mine.
      [1913 Webster]

   3. (Astron.) A constellation of the southen hemisphere; --
      called also the Cup.
      [1913 Webster]