What is another word for "concealed"?

Roget's Thesaurus (1911) lists these synonyms for "concealed": abditory, adytum, ambuscade, ambush, anagram, and, arcanum, back, background, behind, blend, blind, blinker, blush, book, born, charade, cloak, closet, cloud, conceal, concealment, confidential, conundrum, cover, covered, covert, crack, crux, crypt, curtain, danger, dark, dead, deceive, delitescence, delitescent, difficulty, dim, disguise.