| fallible(adjective, unpredictable, unreliable, fickle, variable) |
| fantastic(adjective, strange, odd, unlikely, unbelievable) |
| farfetched(adjective, unreasonable, suspect, shady, unlikely) |
| fatalistic |
| foolish(adjective, ridiculous) |
| fuzzy(vague, unclear, ambiguous, misleading, indistinct) |
| grotesque(adjective, ridiculous) |
| hallucinatory(adjective, unpredictable, fickle, variable, undependable) |
| hard to believe(expression, adjective, idiom) |
| hesitating(adjective, slow, uncertain, shy, hesitant) |
| imaginary(adjective, mythical, fabled, mythological) |
| impossible(adjective, extraordinary, unreasonable, amazing, unlikely) |
| inconstant(adjective, weak, false, loose, uncertain) |
| indisposed(slow, shy, averse, unwilling, reluctant) |
| inexplicit(adjective, uncertain, vague, unclear, ambiguous) |
| infamous(adjective, disreputable) |
| infidel |
| iniquitous |
| insulting |
| irregular(unusual, strange, doubtful, vague, unreliable) |