IMPROB'ABLE, adjective [Latin 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.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI