improbable

adj

1. Not likely to be true.

   “It's highly improbable that aliens abducted you.”

   “Improbabile, that cannot be prooued, improbable.”

   “Nay, if he be of a proud humour, […] he will not Bate an Ace of abſolute certainty, but however doubtful or improbable the thing is, coming f[r]om him it muſt go for an indiſputable truth.”

   “It is highly improbable that the drafter of the notice ever visualised the form that heavy vehicles of the future would take, but the comprehensive wording still covers modern types.”

2. Not likely to happen.

   “Due to the loss of power, it is improbable that we will begin on time.”