Pennatula \Pen*nat"u*la\, n.; pl. L. Pennatul[ae], E. Pennatulas. [NL., fr. L. penna a feather.]

(Zo["o]l.) Any one of numerous species of Pennatula, Pteroides, and allied genera of Alcyonaria, having a featherlike form; a sea-pen. The zooids are situated along one edge of the side branches.

Source: Webster's Revised Unabridged Dictionary (1913)