n. 侦探, 间谍活动, 观察

[法] 间谍, 侦察, 探索

[ noun ]
the act of detecting something; catching sight of something
<noun.act>

Espial \Es*pi"al\, n. [OE. & Norm. F. espiaille. See {Espy}.]
1. The act of espying; notice; discovery.

Screened from espial by the jutting cape. --Byron.

2. One who espies; a spy; a scout. [Obs.] ``Their espials . .
. brought word.'' --Holland.