derny/ˈdɜː(ɹ)ni/EtymologyBorrowed from French derny, named after the French manufacturer of the original derny bicycle, Roger Derny et Fils.derny means A motorized bicycle for paced cycling events such as keirin. Lexicurio rates it Sui generis — a strength score of 89 out of 100.nounA motorized bicycle for paced cycling events such as keirin.“Of course, a familiar sight in a velodrome is the derny, with its characteristic engine sound. Before the cyclists come onto the track, the derny riders perform a few laps to warm up their engines.”