Definition of derring-do

Word Originlate 16th cent.: from late Middle English dorryng do ‘daring to do’, used by Chaucer, and, in a passage by Lydgate based on Chaucer's work, misprinted in 16th-cent. editions as derrynge do; this was misinterpreted by Spenser to mean ‘manhood, chivalry’, and subsequently taken up and popularized by Sir Walter Scott.