The Collaborative International Dictionary of English v.0.48:

Lyrate \Ly"rate\, Lyrated \Ly"ra*ted\, a. [NL. lyratus. See
   Lyre.]
   1. (Bot.) Lyre-shaped, or spatulate and oblong, with small
      lobes toward the base; as, a lyrate leaf.
      [1913 Webster]

   2. (Zool.) Shaped like a lyre, as the tail of the blackcock,
      or that of the lyre bird.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lyrate
    adj 1: (of a leaf shape) having curvature suggestive of a lyre