The tilde (/ˈtɪldə/; ˜ or ~) is a grapheme with several uses. The name of the character came into English from Spanish, which in turn came from the Latin titulus, meaning "title" or "superscription".

The reason for the name was that it was originally written over a letter as a scribal abbreviation, as a "mark of suspension", shown as a straight line when used with capitals. Thus the commonly used words Anno Domini were frequently abbreviated to A Dñi, an elevated terminal with a suspension mark placed over the "n". Such a mark could denote the omission of one letter or several letters. This saved on the expense of the scribe's labour and the cost of vellum and ink. Medieval European charters written in Latin are largely made up of such abbreviated words with suspension marks; only uncommon words were given in full. The tilde has since been applied to a number of other uses as a diacritic mark or a character in its own right. These are encoded in Unicode at U+0303◌̃COMBINING TILDE and U+007E~TILDE (as a spacing character), and there are additional similar characters for different roles. In lexicography, the latter kind of tilde and the swung dash (⁓) are used in dictionaries to indicate the omission of the entry word.