1
- (of a person or their activities) involved in or involving secret work within a community or organization, especially for the purposes of police investigation or espionage（尤指警方调查或间谍）秘密工作的：
an undercover police operation.
秘密警察行动。
2
- provided with shelter有覆盖物的; 有外套的：
undercover seating.
有外套座。
- as an undercover agent任密探（或特工）：
he worked undercover in Northern Ireland.
他在北爱尔兰从事密探工作。