spy has definitions from the field of military
1
[ noun ] (military) a secret agent hired by a state to obtain (military) information about its enemies or by a business to obtain industrial secrets from competitors

Synonyms

undercover_agent

Used in print

(John Dos Passos, Midcentury....)

`` Oh he 's just an international spy '' , Eileen would shout with her screechy laugh .

(Guy Bolton, The Olympians....)

He refused to bring Claire to it even as an occasional visitor , claiming that his every move was watched by spies of the Milbankes .

2
[ verb ] catch sight of

Synonyms

spot espy descry

Used in print

(Louis Zara, Dark Rider....)

South of Laurel_Grove_Cemetery , and below the junction of the Neversink and the Delaware , was the Tri-State_Rock , from which Stevie could spy New_Jersey and Pennsylvania , as_well_as New_York , simply by spinning around on his heel .

Related terms

sight detection discoverer

3
[ verb ] watch, observe, or inquire secretly

Synonyms

snoop sleuth stag

Used in print

(Dolores Hitchens, Footsteps in the Night....)

You should have gone_to work today , ' stead of sneaking around spying on the Dronk house '' .

What on_earth was in Mae 's mind , that she wanted him up there spying on what the cops were doing ?

4
[ noun ] a secret watcher; someone who secretly watches other people

Examples

"my spies tell me that you had a good time last night"

Related terms

spectator snoop snoop tail

5
[ verb ] secretly collect sensitive or classified information; engage in espionage

Examples

"spy for the Russians"

Related terms

investigate

*