derring-don.

derring-doderring-do: [16] Derring-do arose from a misunderstanding of the Middle English phrase dorring do, which literally meant ‘daring to do’ (dorren was the Middle English form of dare). In some 16th-century editions of medieval authors this was misprinted as derring do. The poet Edmund Spenser came across it and used it several times in his often deliberately archaic verse – but as a noun, meaning ‘boldness’, rather than as the verbal phrase it actually was: ‘a man of mickle name, renowned much in arms and derring do’, Faerie Queene 1596. Spenser’s usage was picked up and popularized by Sir Walter Scott in the early 19th century.=> darederring-do (n.)originally (late 14c.) dorrying don, literally "daring to do," from durring "daring," present participle of Middle English durren "to dare" (see dare (v.)) + don, infinitive of do (v.). Misspelled derrynge do 1500s and mistaken for a noun by Spenser, who took it to mean "manhood and chevalrie;" picked up from him and passed on to Romantic poets as a pseudo-archaism by Sir Walter Scott.