| theoretical(adjective, fake, false, silly, impractical) |
| thin(adjective, extraordinary, strange, unreasonable, dubious) |
| unbelievable(adjective, extraordinary, strange, unreasonable, dubious) |
| unconvincing(adjective, extraordinary, strange, unreasonable, dubious) |
| unheard-of(adjective, extraordinary, strange, unbelievable, implausible) |
| unknowable(adjective, extraordinary, belief, strange, unbelievable) |
| unlikely(adjective, extraordinary, strange, unbelievable, implausible) |
| unreal(adjective, fake, silly, imaginary, unlikely) |
| unrealistic(adjective, practical, unlikely, idealistic, believable) |
| unsubstantial(adjective, extraordinary, strange, unreasonable, dubious) |
| unthinkable(adjective, extraordinary, strange, unbelievable, implausible) |
| weak(adjective, extraordinary, strange, unreasonable, dubious) |
| aerial(adjective, fake, false, imaginary, fanciful) |
| artificial(adjective, fake, false, imaginary, fanciful) |
| beyond belief(expression, unbelievable, unthinkable, unimaginable) |
| chimerical(adjective, fake, false, imaginary, fanciful) |
| delusive(adjective, fake, false, imaginary, fanciful) |
| doubtful(adjective, unreasonable, dubious, unlikely, flimsy) |
| dreamlike(adjective, fake, false, imaginary, fanciful) |
| dubious(adjective, unreasonable, unlikely, flimsy, unbelievable) |