doubtdoubt

The story

The verb is derived from Middle English douten (‘to doubt, fear, worry’) [and other forms], from Old French douter, doter, duter (compare Middle French doubter), from Latin dubitāre (‘to be uncertain, doubt; to hesitate, waver in coming to an opinion; to consider, ponder’); the further etymology is uncertain, but one theory is that dubitō may be derived from dubius (‘fluctuating, wavering; doubtful, dubious, uncertain’), from duhibius (‘held as two’), from duo (‘two’) (ultimately from Proto-Indo-European *dwóh₁ (‘two’)) + habeō (‘to have, hold’) (possibly ultimately from Proto-Indo-European *gʰeh₁bʰ- (‘to grab, take’)).1disputed Scholars disagree here; the competing view is quoted as the source gives it. Spelling reformers of the early modern period added the letter b to reflect the Latin root dubitō, but it has never been pronounced in English. The ESL "question" sense is a semantic loan from Romance cognates: Portuguese dúvida, Spanish duda, Catalan dubte, French doute, Italian dubbio and others, which can all mean "question".

Full etymology on Wiktionary