pilot biscuit

from WordNet (r) 3.0 (2006)

pilot biscuit
    n 1: very hard unsalted biscuit or bread; a former ship's staple
         [syn: {hardtack}, {pilot biscuit}, {pilot bread}, {sea
         biscuit}, {ship biscuit}]

from The Collaborative International Dictionary of English v.0.48

Hardtack \Hard"tack`\ or Hard-tack
\Hard"-tack`\(h[aum]rd"t[a^]k`), n.
   1. A name given by soldiers and sailors to a kind of
      unleavened hard biscuit or sea bread. Called also {pilot
      biscuit}, {pilot bread}, {ship biscuit} and {ship bread}
      [1913 Webster]

   2. Any of several mahogany trees, esp. the {Cercocarpus
      betuloides}. --MW10
      [PJC]