| universal(adjective, abstract, theoretical, abstruse, philosophical) |
| unknowable(adjective, obscure, dark, superior, supernatural) |
| unknown(adjective, obscure, dark, superior, mysterious) |
| unnatural(adjective, obscure, dark, superior, mysterious) |
| unphysical(adjective, abstract, theoretical, abstruse, philosophical) |
| unreal(adjective, amazing, abstract, astonishing, astounding) |
| unrevealed(adjective, obscure, dark, superior, supernatural) |
| unsubstantial(adjective, abstract, theoretical, abstruse, philosophical) |
| unusual(adjective, obscure, dark, superior, mysterious) |
| unworldly |
| apparitional(adjective, demoniac, unspecific, supermundane) |
| bizarre(paranormal, mystic, mystical) |
| conjectural(abstract, theoretical, philosophical) |
| corpselike(adjective, demoniac, unspecific, supermundane) |
| demoniac(adjective, unspecific, supermundane) |
| difficult to catch(expression, adjective, idiom, demoniac, unspecific) |
| eidolic(adjective, demoniac, unspecific, supermundane) |
| elusive(adjective, demoniac, unspecific, supermundane) |
| elusory(adjective, demoniac, unspecific, supermundane) |
| ghostlike(paranormal, mystic, mystical) |