The first or introductory principle of an art, science, etc.

(常用复数)(艺术,科学等之)初步；基本原理；入门。

Anything in the first state of development; a beginning.

发端；起源。

An incompletely developed organ or part; specif. a vestigial organ or part with no functional activity.

发育不完全的器官；退化的器官。