We don't have synonyms for incognita yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are incognito, incognitos and incognitas.
(n) :
one unknown or in disguise, or under an assumed character or name; the assumption of disguise or of a feigned character; the state of being in disguise or not recognized
(n) :
one unknown or in disguise, or under an assumed character or name; the assumption of disguise or of a feigned character; the state of being in disguise or not recognized