Definition of "undercover" []

• Performed or occurring in secret: an undercover investigation. (adjective)
• Engaged or employed in spying or secret investigation: undercover FBI agents. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Back in 1981, the phrase "undercover officer" took on a new meaning during the wedding of Prince William's parents."
• "Not attached to any particular group, but the idea of going in undercover and eventually putting your plan into effect, through which you may be revealed (either through discovery or death) or not (failure or total success) … …. leftover"
• "*** AUGGIE/VIOLET: The showrunners did a stupid move by not keeping the dismissal of ASW and Colin undercover until next january."