Source : 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. (Zo["o]l.) A color marking or structure on the head
      somewhat resembling a hood.