Definition of "vestigial" in English

adjective

Of or pertaining to a vestige or remnant; like a trace from the past.
Not fully developed in mature animals.
(evolutionary theory) Of a vestigial structure; that has lost all or most of its original function in the course of evolution.

noun

(evolutionary theory) A small, degenerate, or imperfectly developed part or organ which has been more fully developed in some past generation.