Source : Webster's Revised Unabridged Dictionary (1913)

Rudiment \Ru"di*ment\, n. [L. rudimentum, fr. rudis unwrought,
   ignorant, rude: cf. F. rudiment. See {Rude}.]
   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. (Biol.) An imperfect organ or part, or one which is never
      developed.

Rudiment \Ru"di*ment\, v. t.
   To furnish with first principles or rules; to insrtuct in the
   rudiments. --Gayton.

Source : WordNet®

rudiment
     n 1: the elementary stages of any subject (usually plural); "he
          mastered only the rudiments of geometry" [syn: {first
          rudiment}, {first principle}, {alphabet}, {ABC}, {ABC's},
           {ABCs}]
     2: the remains of a body part that was functional at an earlier
        stage of life; "Meckel's diverticulum is the rudiment of
        the embryonic yolk sac"