The Collaborative International Dictionary of English v.0.48:
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. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Surveillant \Sur*veil"lant\, a. Overseeing; watchful. [1913 Webster]