Dud/dʌd/ Definition 1 of 3Pro Tip 1/3Item Quality Use 'dud' to describe something ineffective or of poor quality. I bought these cheap headphones, but they're duds. Pro Tip 2/3Expectation vs Reality Express disappointment when something doesn't meet expectations. The movie was a total dud compared to its trailer. Pro Tip 3/3Electronic Devices Commonly used when electronic devices malfunction. My new laptop won’t start; it’s a complete dud.