Emily Dickinson Lexicon

IM-PROB'A-BLE, a. [Sp. Fr. from L. improbabilis; in and probabilis, from probo, to prove.]

Not likely to be true; not to be expected under the circumstances of the case. It is always improbable that men will knowingly oppose their own interest; yet the fact is possible. It is improbable that snow will fall in July, but not incredible.