ラテン語の dubius, ii が語源で、語源的には dubious と同じ。 dubious, doubtful の派生語。
英語の語源
doubt
doubt: [13] English acquired the verb doubt from Old French doter or duter, a descendant of Latin dubitāre ‘waver, be uncertain’ (the b was reintroduced from the Latin spelling in the 15th century). Dubitāre was closely related to Latin dubius ‘uncertain’ (ultimate source of English dubious [16]), which appears to have been based on duo ‘two’, and thus to have meant originally ‘wavering between two possibilities’. In Old French, the sense ‘fear’ developed, and this was an important meaning of the word in Middle English; it survives in the derivative redoubtable [14], literally ‘fearable’. => dubious, redoubtable
doubt (v.)
early 13c., "to dread, fear," from Old French doter "doubt, be doubtful; be afraid," from Latin dubitare "to doubt, question, hesitate, waver in opinion" (related to dubius "uncertain;" see dubious), originally "to have to choose between two things."
The sense of "fear" developed in Old French and was passed on to English. Meaning "to be uncertain" is attested in English from c. 1300. The -b- was restored 14c. by scribes in imitation of Latin. Replaced Old English tweogan (noun twynung), from tweon "two," on notion of "of two minds" or the choice of two implied in Latin dubitare (compare German Zweifel "doubt," from zwei "two").
doubt (n.)
early 13c., from Old French dote (11c.) "fear, dread; doubt," from doter (see doubt (v.)).
例文
1. There can be little doubt that he will offend again.
彼が再犯することは言うまでもない。
2.They have the usual quota of human weaknesses,no doubt .
彼らにも共有されている弱点があることは間違いありません。
3.This new information does throw doubt on their choice.
という新しい情報は確かに彼らの選択に疑問を抱かせた。
4.There was no doubt in his mind that the man was serious.