2268: doubt and 2 Mar 2, 2021
Though it may not be too surprising that the word for ‘doubt’ is also related to words for ‘two’ including ‘duo’ and indeed ‘two, but keep in mind this replaced an earlier word with the same quality: Old English ‘twēo’ (doubt) from the same root as ‘two’. Likewise, the German word for doubt is ‘Zweifel’ which clearly has the root ‘zwei’ (two) in it. Moreover, the Latin root ‘dubitāre’, which led to the current English word is thought to come from habeō (I have), combined with the Proto-Indo-European *dwóh₁ “two” as in ‘holding two’ making the word seemingly even more literal, but actually the sense in Latin would be closer to ‘hesitate’.
Notably, the word ‘doubt’ in Middle English was not spelt with a B, but this was added later to correspond with the Latin root even though the Old French root, and the modern French derivative ‘douter’ (to doubt) aren’t spelt that way.