Dud/duds

‘Dud’ in the sense of something that fails to work or function dates from the early 19th century, and two such items would both be ‘duds’, but ‘duds’ in the plural is also colloquial for ‘clothes’ and this usage is very much older, from at least the 1300s, according to the OED. The etymology for both these senses of the word is unknown. In Thomas Harman’s glossary, published in 1566, ‘duds’ (spelt ‘dudes’) meaning ‘clothes’ is classified as ‘cant’ or slang, but today this usage of ‘duds’, throughout the English-speaking world, would be considered colloquial rather than slang.