Unobserved (adjective)

Not noticed or seen; without being observed.

Origin:

Late middle english: from un-1 "not" + observed, past participle of observe.

Examples:

1. The criminal slipped away unnoticed and remained unobserved until the next morning.
2. The microscopic organisms were unobserved by the naked eye.
3. The insects lived unobserved in their natural habitat.
4. The minor technical faults went unobserved by the crew.
5. The experiment was conducted unobserved to eliminate potential bias.