Webster’s Revised Unabridged Dictionary · 1913
Cucullus
Cu·cul′lus, n.; pl. Cuculli (#). [L., a hood.] 1. (Bot.) A hood-shaped organ, resembling a cowl or monk's hood, as certain concave and arched sepals or petals.
2. (Zoöl.) A color marking or structure on the head somewhat resembling a hood.