Source : Webster's Revised Unabridged Dictionary (1913)

Raider \Raid"er\, n.
   One who engages in a raid. [U.S.]

Source : WordNet®

raider
     n 1: someone who takes spoils or plunder (as in war) [syn: {plunderer},
           {pillager}, {looter}, {spoiler}, {despoiler}, {freebooter}]
     2: a corporate investor who intends to take over a company by
        buying a controlling interest in its stock and installing
        new management