From The Collaborative International Dictionary of English v.0.48 [gcide]:
Spy \Spy\ (sp[imac]), v. t. [imp. & p. p. Spied (sp[imac]d);
p. pr. & vb. n. Spying.] [OE. spien, espien, OF. espier, F.
['e]pier, OHG. speh[=o]n, G. sp[aum]hen; akin to L. specere
to see, Skr. spa[,c]. [root] 169. Cf. Espy, v. t.,
Aspect, Auspice, Circumspect, Conspicuous, Despise,
Frontispiece, Inspect, Prospect, Respite, Scope,
Specimen, Spectacle, Specter, Speculate, Spice,
Spite, Suspicion.]
1. To gain sight of; to discover at a distance, or in a state
of concealment; to espy; to see.
[1913 Webster]
One, in reading, skipped over all sentences where he
spied a note of admiration. --Swift.
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2. To discover by close search or examination.
[1913 Webster]
Look about with your eyes; spy what things are to be
reformed in the church of England. --Latimer.
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3. To explore; to view, inspect, and examine secretly, as a
country; -- usually with out.
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Moses sent to spy out Jaazer, and they took the
villages thereof. --Num. xxi.
32.
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From WordNet (r) 3.0 (2006) [wn]:
spying
n 1: keeping a secret or furtive watch
2: the act of keeping a secret watch for intelligence purposes
[syn: spying, undercover work]
3: the act of detecting something; catching sight of something
[syn: detection, catching, espial, spying,
spotting]