Source : Webster's Revised Unabridged Dictionary (1913)

Paillasse \Pail*lasse"\ (?; F. ?), n. [F., fr. paille straw. See
   {Pallet} a bed.]
   An under bed or mattress of straw. [Written also
   {palliasse}.]

Source : WordNet®

paillasse
     n : mattress consisting of a thin pad filled with straw or
         sawdust [syn: {palliasse}]