imprŏbābĭlis — Lewis & Short
imprŏbābĭlis (inpr-), e, adj.2. inprobabilis,
motus animi,Sen. Ep. 75 med.:
factum per se improbabile,Quint. 7, 4, 7:
argumentum,Plin. 4, 13, 27, § 93:
non improbabilis mos,Dig. 50, 14, 3.—Adv.: imprŏbābĭlĭter, objectionably:
objecta non improbabiliter,Sid. Ep. 1, 11 med.