un‧de‧tect‧ed /ˌʌndɪˈtektəd◂, ˌʌndɪˈtektɪd◂/
adjective if something, especially something bad, goes undetected, no one notices it
go/remain undetected
Doctors can make mistakes and diseases can remain undetected. The thieves escaped undetected through a basement window. [TahlilGaran] Dictionary of Contemporary English ▲