The Collaborative International Dictionary of English v.0.48:

Lunate \Lu"nate\, Lunated \Lu"na*ted\, a. [L. lunatus
   crescent-shaped, p. p. of lunare to bend like a crescent, fr.
   luna the moon.]
   Crescent-shaped; resembling the crescent moon; as, a lunate
   leaf; a lunate beak; a lunated cross. --Gray.

   Syn: lunular, bicephalous, crescent(prenominal),
        crescent-shaped.
        [1913 Webster]

WordNet (r) 3.0 (2006):

lunate
    adj 1: resembling the new moon in shape [syn: crescent(a),
           crescent-shaped, semilunar, lunate]