improbable
adj 1: not likely to be true or to occur or to have occurred; "legislation on the question is highly unlikely"; "an improbable event" [syn: unlikely] [ant: probable]
2: having a probability to low to inspire belief [syn: unbelievable, unconvincing, unlikely] 3: too improbable to admit of belief; "a tall story" [syn: marvelous, marvellous, tall(a)]
