Source : Webster's Revised Unabridged Dictionary (1913)

Beefeater \Beef"eat`er\, n. [Beef + eater; prob. one who eats
   another's beef, as his servant. Cf. AS. hl[=a]f?ta servant,
   properly a loaf eater.]
   1. One who eats beef; hence, a large, fleshy person.

   2. One of the yeomen of the guard, in England.

   3. (Zo["o]l.) An African bird of the genus {Buphaga}, which
      feeds on the larv[ae] of botflies hatched under the skin
      of oxen, antelopes, etc. Two species are known.

Source : WordNet®

beefeater
     n : officer in the (ceremonial) bodyguard of the British monarch
         [syn: {yeoman}, {yeoman of the guard}]