Source : Webster's Revised Unabridged Dictionary (1913)

Troilus \Tro"i*lus\, n.; pl. L. {Troili}, E. {Troiluses}. [NL.,
   fr. L. Troilus, Gr. ?, the son of Priam.] (Zo["o]l.)
   A large, handsome American butterfly ({Euph[oe]ades, or
   Papilio, troilus}). It is black, with yellow marginal spots
   on the front wings, and blue spots on the rear wings.