sur·veil·lant 
(sər-vālənt)
(sər-vālənt)adj.
Exercising surveillance.
n.
One that exercises surveillance.
[French, present participle of surveiller, to watch over : sur-, over (from Old French; see SUR-) + veiller, to watch (from Old French veillier, from Latin vigilāre, from vigil, watchful; see weg- in the Appendix of Indo-European roots).]
- at the end of one's tether
- at the end of rope
- at the end of tether
- at the end of the day
- at thehand
- at thehand/handsof
- at the latest
- at the mercy of
- at (the) most
- at the most
- at the ready
- at the same time
- at the top of lungs
- at the top of (one's) lungs
- at the top of one's lungs
- at the top of (one's) voice
- at the top of one's voice
- at the top of voice
- at the wheel
- at (the) worst
- at the worst
- attic
- Attic
- Attica
- Atticism