| nonplussing |
| odd(adjective, extraordinary, unusual, strange, remarkable) |
| outlandish(extraordinary, unusual, strange, exceptional, remarkable) |
| peculiar(adjective, extraordinary, unusual, strange, odd) |
| prodigious(extraordinary, exceptional, remarkable, particular) |
| shady(unusual, strange, unexpected) |
| sphinxlike(dark, strange, uncertain, mysterious, inexplicable) |
| spooky |
| subtle(adjective, hard, obscure, vague, tricky) |
| tangled(adjective, hard, obscure, complex, sophisticated) |
| troubling(verb, awkward, uneasy, uncomfortable) |
| uncomprehensible(adjective, incomprehensible) |
| unfamiliar |
| unheard-of(strange, unfathomable) |
| unknowable(strange, unfathomable, impenetrable, opaque, unintelligible) |
| unknown(strange, unclear, indistinct, indistinguishable, inexplicable) |
| unprecedented(extraordinary, remarkable, particular) |
| unusual(extraordinary, strange, odd, different, remarkable) |
| weird(adjective, extraordinary, unusual, strange, exceptional) |
| Daedalean(adjective, hard, fancy, obscure, difficult) |