| peculiar(adjective, unknown, untried) |
| undiscovered(adjective, strange, mysterious, indefinite) |
| X(strange, mysterious, indefinite, unidentified) |
| incog(strange, mysterious, indefinite, unidentified) |
| incognito(strange, indefinite, unidentified) |
| little known(expression, strange, mysterious, unknown) |
| mysterious(strange, unknown, indefinite, alien) |
| original(last, unknown, primitive, outdated) |
| so-and-so(strange, mysterious, indefinite, unidentified) |
| such-and-such(strange, mysterious, indefinite, unidentified) |
| unaccustomed(experience, distant, different, unknown) |
| unapprehended(strange, mysterious, indefinite, unidentified) |
| unascertained(strange, mysterious, indefinite, unidentified) |
| uncelebrated(strange, mysterious, indefinite, unidentified) |
| uncharted(adjective, strange, mysterious, unknown) |
| undistinguished(strange, indefinite, unidentified) |
| unexplained(strange, mysterious, indefinite, unidentified) |
| unexplored(experience, strange, different, mysterious) |
| unheard-of(strange, doubtful, dubious, indefinite) |
| unidentified(strange, mysterious, indefinite) |