| passionless(adjective, cool, blank, aloof, unemotional) |
| past comprehension |
| placid(adjective, quiet, cool, moderate, gentle) |
| reserved(adjective, cool, blank, aloof, unemotional) |
| serene(adjective, quiet, cool, moderate, gentle) |
| sibylline(solid, dark, uncertain, mysterious, dense) |
| spooky |
| stoic(adjective, cool, blank, aloof, unemotional) |
| stoical(adjective, cool, blank, aloof, unemotional) |
| stolid(adjective, dull, cool, dead, blank) |
| tranquil(adjective, quiet, cool, still, peaceful) |
| transcendental(strange, supernatural, spiritual, mystical, inexplicable) |
| uncanny |
| unclear |
| undecipherable(adjective, unintelligibility) |
| unexcitable(adjective, quiet, cool, moderate, gentle) |
| unflappable(adjective, quiet, cool, moderate, gentle) |
| unknown |
| unreadable(adjective, blank, hidden, unfathomable, enigmatic) |
| unsolvable(adjective, solved) |