Synonyms and related words :
absurd, crazy, distant, doubtable, doubtful, dubious, dubitable, extraordinary, fanciful, farfetched, fishy, flimsy, forced, hard to believe, hardly possible, implausible, impossible, inconceivable, incredible, insane, ludicrous, mad, more than doubtful, more than expected, out-of-the-way, past expectation, peculiar, questionable, quite another thing, remote, ridiculous, something else again, strained, strange, sudden, thin, unannounced, unanticipated, unbelievable, unconvincing, undivined, unexpected, unforeseeable, unforeseen, unguessed, unheralded, unhoped for, unlikely, unpredictable, unpredicted, unprepared for, unpromising, unrealistic, unsubstantial, unthinkable, weak, weird, wild, without warning