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spy (up)on someone or something

to watch someone or something to learn secret or concealed information. (Upon is formal and less commonly used than on.) Are you spying upon me? I wasn't spying on you! I was just trying to see who you were.
See also: on, spy

spy on

Secretly or furtively observe someone or something, as in The children loved spying on the grownups, or The company sent him to spy on the competitor's sales force. [Early 1600s]
See also: on, spy

ˌspy out the ˈland

find out about a situation, a place, an organization, etc. before you make a decision: The manager is sending Mark to Iceland to spy out the land. He wants to know whether we can do business there.
See also: land, out, spy

spy on

or spy upon
To observe someone or something secretly and closely: A detective had been spying on the mayor's every move for months. The children spied upon their neighbors from the bushes along the property line.
See also: on, spy

spy out

1. To observe some place secretly and closely: The troops spied out the cave and decided it was safe to hide there. The explorers sent a scout into the valley to spy it out before descending.
2. To discover something by observing secretly and closely: Try to spy out what's going on on those rooftops. We followed the other teams' strategies carefully to spy them out.
See also: out, spy
References in periodicals archive ?
iKeyMonitor Free Android Spy is a lite edition of iKeyMonitor Android Spy.
In one sequence shot off the coast of Costa Rica in Central America, a 15mph Spy Dolphin guided by experts in a highspeed inflatable boat, easily kept pace with real-life spinner dolphins which can cover 250 miles a day.
Andrew says he is a fan of spy movies like Tinker Tailor Solider Spy and he and the Legacy cast met a retired spy as part of their research.
Characteristics such as resourcefulness, observation skills, nerve, empathy, and discretion were the ones that spy recruiters found helpful among domestic agents.
I Spy Super Challenger combines I Spy's intriguing photographs and riddles with fast-paced arcade-style games.
It allows video and audio playback, and uploads to Spy Net HQ.
During their mission, trainee spies will get to grips with the very latest spy gadgets, as they infiltrate a shadowy organisation, evade counter-surveillance and escape without detection.
A KGB cable in the Venona files identifies a spy code-named "Ales" at the State Department whose biographical details match only Hiss.
Here, expert on CIA operations Tom Mangold discusses the technical brilliance used by the USA to spy on Russia and their failure to tell President Reagan he was pushing them into a state of nuclear paranoia.
Austrian-based Altova Inc has introduced XML Spy 4.
Hanssen, the FBI says, had been a spy for Moscow for 15 years.
The physicist, who has pleaded not guilty, is accused of being a spy for China.
HOLIER-THAN-THOU guardians of morality round the world are - almost - lost for words when it comes to translating the name of one of the year's greatest box-office blockbuster films, Austin Powers: the Spy Who Shagged Me.
I Spy Spooky Mansion" takes kids on a journey through a mysterious old mansion filled with innovative, brain-building games for children ages six through ten; while "I Spy Junior" introduces charming picture riddles, games, and puzzles for children ages three through five.