Webster's Revised Unabridged Dictionary · 1913

Pinna

Pinna , noun

[Latin, a feather.]

1.
(a) (Botany) A leaflet of a pinnate leaf. See Illust. of Bipinnate leaf, under Bipinnate.
(b)
(Botany) One of the primary divisions of a decompound leaf.
2.
(Zoology) One of the divisions of a pinnate part or organ.
3.
(Zoology) Any species of Pinna, a genus of large bivalve mollusks found in all warm seas. The byssus consists of a large number of long, silky fibers, which have been used in manufacturing woven fabrics, as a curiosity.
4.
(Anatomy) The auricle of the ear. See Ear.