From Webster's Revised Unabridged Dictionary (1913) :
Flunky \Flun"ky\, n.; pl. Flunkies. [Prob. fr. or akin to
flank.] [Written also flunkey.]
1. A contemptuous name for a liveried servant or a footman.
2. One who is obsequious or cringing; a snob.
3. One easily deceived in buying stocks; an inexperienced and
unwary jobber. [Cant, U.S.]