dubius

1. (adjective, declension-1, declension-2) Moving in two directions alternately, vibrating to and fro, fluctuating, wavering
2. (adjective, declension-1, declension-2, figuratively) Vacillating in mind, wavering, uncertain, doubting, doubtful, dubious, irresolute, undetermined
3. (adjective, declension-1, declension-2) Precarious, dangerous, critical, difficult, adverse, doubtful, in doubt
4. (adjective, declension-1, declension-2) Changeable, uncertain

Opposite of

fixus, prōmptus, indubius

Pronounced as (IPA)

[ˈdʊ.bi.ʊs]

Etymology

Somewhat uncertain, but likely derived from *dubos (“in doubt”, adj.), from Proto-Italic *du(i)βwos, from Proto-Indo-European *dwi- (“two-”) + *bʰuH- (“to be”), with the same latter element as in superbus, probus (less likely tribus), in this case parallel to Ancient Greek διφυής (diphuḗs, “of two shapes or natures”). Or less likely, directly from Proto-Indo-European *dubʰi- (“on two sides”).
For the relation to "two" cf. Ancient Greek δισσός (dissós, “twofold; doubtful”), δοιάζω (doiázō, “to be in two minds”) and German Zweifel (“doubt”).

Concepts

doubtful

doubting

inconclusive

indecisive

questionable

dubitative

dubersome

Synonyms

diversus

dubitabilis