The Collaborative International Dictionary of English v.0.48:

Fritillary \Frit"il*la*ry\, n.
   1. (Bot.) A plant with checkered petals, of the genus
      Fritillaria: the Guinea-hen flower. See Fritillaria.
      [1913 Webster]

   2. (Zool.) One of several species of butterflies belonging to
      Argynnis and allied genera; -- so called because the
      coloring of their wings resembles that of the common
      Fritillaria. See Aphrodite.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fritillary
    n 1: any liliaceous plant of the genus Fritillaria having
         nodding variously colored flowers [syn: fritillary,
         checkered lily]
    2: butterfly with brownish wings marked with black and silver