köken: Learned borrowing from Ancient Greek ἀμφίβολος (amphíbolos). For sense "questionable", semantic loan from French douteux. Morphologically, αμφι- (amfi-) + stem βολ- for which see αμφιβάλλω (amfivállo, “Ι doubt”) - αμφιβολία f (amfivolía) & βάλλω (vállo) - βολή (volí) + suffix -ος (-os).
köken: From Early Middle Japanese adjective 疑(うたが)わし (utagawashi), with the 終(しゅう)止(し)形(けい) (shūshikei, “predicative form”) ending in し (shi) first replaced with the 連(れん)体(たい)形(けい) (rentaikei, “attributive form”) ending in しき (shiki), and then with the medial /-k-/ falling out to result in an ending of しい (shii). Ultimately from verb 疑う (utagau, “to doubt; to suspect”).
Moving in two directions alternately, vibrating to and fro, fluctuating, wavering · Vacillating in mind, wavering, uncertain, doubting, doubtful, dubious, irresolute, undetermined · Precarious, dangerous, critical, difficult, adverse, doubtful, in doubt
zıt: fixus, prōmptus, indubius
köken: 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…