Source : Webster's Revised Unabridged Dictionary (1913)

Redcoat \Red"coat`\ (-k[=o]t`), n.
   One who wears a red coat; specifically, a red-coated British
   soldier.

Source : WordNet®

redcoat
     n : British soldier; so-called because of his red coat
         (especially during the American Revolution) [syn: {lobsterback}]