Source : Webster's Revised Unabridged Dictionary (1913)

Hassock \Has"sock\, n. [Scot. hassock, hassik, a besom, anything
   bushy, a large, round turf used as a seat, OE. hassok sedgy
   ground, W. hesgog sedgy, hesg sedge, rushes; cf. Ir. seisg,
   and E. sedge.]
   1. A rank tuft of bog grass; a tussock. --Forby.

   2. A small stuffed cushion or footstool, for kneeling on in
      church, or for home use.

            And knees and hassocks are well nigh divorced.
      --Cowper.

Source : WordNet®

hassock
     n 1: thick cushion used as a seat [syn: {ottoman}, {pouf}, {pouffe},
           {puff}]
     2: a cushion for kneeling on (as when praying in church)