1. That which is unformed or undeveloped; the principle which lies at the bottom of any development; an unfinished beginning. but I will bring thee where thou soon shalt quit Those rudiments, and see before thine eyes The monarchies of the earth. (milton) the single leaf is the rudiment of beauty in landscape. (I. Taylor)
2. Hence, an element or first principle of any art or science; a beginning of any knowledge; a first step. This boy is forest–born, And hath been tutored in the rudiments of many desperate studies. (Shak) There he shall first lay down the rudiments Of his great warfare. (milton)
3. (Science: biology) An imperfect organ or part, or one which is never developed.
Origin: L. Rudimentum, fr. Rudis unwrought, ignorant, rude: cf. F. Rudiment. See Rude.