Webster's Revised Unabridged Dictionary · 1913

Acantha

Acantha ({not transcribed}) , noun

[Greek {not transcribed} thorn, from {not transcribed} point. See Acute.]

1.
(Botany) A prickle.
2.
(Zoology) A spine or prickly fin.
3.
(Anatomy) The vertebral column; the spinous process of a vertebra. — Dunglison