Source : Webster's Revised Unabridged Dictionary (1913)

Surveillant \Sur*veil"lant\, n.; pl. {Surveillants}. [F., fr.
   surveiller to watch over. See {Surveillance}.]
   One who watches over another; an overseer; a spy; a
   supervisor.

Surveillant \Sur*veil"lant\, a.
   Overseeing; watchful.