The Collaborative International Dictionary of English v.0.48:

Puffball \Puff"ball`\, n. (Bot.)
   A kind of ball-shaped fungus (Lycoperdon giganteum, and
   other species of the same genus) full of dustlike spores when
   ripe; -- called also bullfist, bullfice, puckfist,
   puff, and puffin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

puffball
    n 1: any of various fungi of the family Lycoperdaceae whose
         round fruiting body discharges a cloud of spores when
         mature [syn: puffball, true puffball]
    2: any of various fungi of the genus Scleroderma having hard-
       skinned subterranean fruiting bodies resembling truffles
       [syn: earthball, false truffle, puffball, hard-skinned
       puffball]