(1):
(a. / adv.) 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.
(2):
(a.) One unknown or in disguise, or under an assumed character or name.
(3):
(a.) The assumption of disguise or of a feigned character; the state of being in disguise or not recognized.