The letter W.
- ‘Why does every Web address start with double-u?’
- ‘Crossing the street, he entered the light pink and white walled diner to find only one stool open at the double-U shaped counter.’
- ‘French double-v is English double-u.’
- ‘We ran a story yesterday we which hoped would solve the irritating need to repeat "double-u, double-u, double-u dot" every time you are talking about a Web site.’
- ‘The double-U shape makes getting stuff in and out quick and simple.’
Late 16th century: the letter W represented as a word.