Incognito

Part of speech: noun (n.)

1. One unknown or in disguise, or under an assumed character or name.

2. The assumption of disguise or of a feigned character; the state of being in disguise or not recognized. His incognito was endangered. Sir W. Scott.

Part of speech: adjective (a.)

Without being known; in disguise; in an assumed character, or under an assumed title; -- said esp. of great personages who sometimes adopt a disguise or an assumed character in order to avoid notice. 'T was long ago Since gods come down incognito. Prior. The prince royal of Persia came thither incognito. Tatler.