verb (used with object)

to discover or catch (a person) in the performance of some act: to detect someone cheating.
to discover the existence of: to detect the odor of gas.
to find out the true character or activity of: to detect a spy.
  1. to rectify alternating signal currents in a radio receiver.
  2. to demodulate.

Origin of detect

1400–50; late Middle English < Latin dētēctus (past participle of dētegere), equivalent to dē- de- + teg(ere) to cover + -tus past participle suffix
Related formsde·tect·a·ble, de·tect·i·ble, adjectivede·tect·a·bil·i·ty, de·tect·i·bil·i·ty, nounpre·de·tect, verb (used with object)un·de·tect·a·ble, adjectiveun·de·tect·a·bly, adverbun·de·tect·ed, adjectiveun·de·tect·i·ble, adjective

Synonym study

2. See learn. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for undetected

Contemporary Examples of undetected

Historical Examples of undetected

  • Jack and myself got in, after putting our heads together, and stole off undetected.

    Ned Myers

    James Fenimore Cooper

  • What shall he profit, if his injustice be undetected and unpunished?

  • Now was her chance to slip down-stairs and, undetected, away.


    Louis Joseph Vance

  • Moreover it was legitimate that I should have been undetected in the summer-house.

    The O'Ruddy

    Stephen Crane

  • As it was, he glided back through the many rooms, undetected.

    Bloom of Cactus

    Robert Ames Bennet

British Dictionary definitions for undetected



not perceived, noticed, or discoveredthe fake bomb passed undetected


verb (tr)

to perceive or noticeto detect a note of sarcasm
to discover the existence or presence of (esp something likely to elude observation)to detect alcohol in the blood
to extract information from (an electromagnetic wave)
obsolete to reveal or expose (a crime, criminal, etc)
Derived Formsdetectable or detectible, adjectivedetecter, noun

Word Origin for detect

C15: from Latin dētectus uncovered, from dētegere to uncover, from de- + tegere to cover
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for undetected

1590s, from un- (1) "not" + past participle of detect. Undetectable is recorded from 1863.



early 15c., from Latin detectus, past participle of detegere "uncover, expose," figuratively "discover, reveal, disclose," from de- "un-, off" (see de-) + tegere "to cover" (see stegosaurus). Related: Detected; detecting.

Online Etymology Dictionary, © 2010 Douglas Harper