undercover
UK: ˌʌndəˈkʌvə | US: ˌʌndərˈkʌvər
adj. engaged in or involving secret work, especially for investigative purposes
n. a person working secretly, especially as a spy or investigator
The word "undercover" combines "under" (Old English under, meaning "beneath" or "below") and "cover" (Old French covrir, from Latin cooperire, meaning "to conceal"). It emerged in the early 20th century to describe clandestine activities, particularly in law enforcement or espionage, where agents "work beneath concealment" to gather information unnoticed. The logic mirrors physical hiding (e.g., under a cover) extended metaphorically to secret roles.
The journalist went undercover to expose corruption in the company.
Undercover agents infiltrated the drug cartel.
She wore an undercover camera to document the illegal activity.
His undercover identity was nearly compromised during the mission.
The police conducted an undercover operation to catch the thieves.