WORD ORIGIN

Middle English from Old French doute (noun), douter (verb), from Latin dubitare ‘hesitate’, from dubius ‘doubtful’the source also of dubious and its derivatives

Mid-16th century: from Latin dubiosus, from dubium ‘a doubt’, neuter of dubius ‘doubtful’

doubter,  doubtful(ly),  doubting,  doubtless,  dubiety,  dubious(ly),  indubitable,  indubitably,  redoubtable,  self-doubt,  undoubted(ly)
Note that redoubt and doubt are not etymologically related.
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Only available upon request