1) Ammunition 2) Bad bomb 3) Bad firecracker 4) Big flop 5) Bomb bomb 6) Bomb not bursting in air 7) Bomb of a bomb 8) Bomb that bombed 9) Bomb that bombs 10) Bomb that fails to explode 11) Boring type 12) Box office bomb 13) Box-office bomb 14) Broadway nightmare 15) Bum bomb 16) Chap is a flop 17) Clinker Found on https://www.crosswordclues.com/clue/dud
[Naval Acronyms and Slang] weather: when not fit to fly â€` e.g. bombs/ammunition failed to explode (RAF) Found on http://www.encyclo.co.uk/local/21733
adjective failing to detonate; especially not charged with an active explosive; `he stepped on a dud mine` Found on https://www.encyclo.co.uk/local/20974
a device, person, or enterprise that proves to be a failure. · a shell or missile that fails to explode after being fired. Found on https://www.infoplease.com/dictionary/dud