a symbol having the shape of a wavy line (-) and the size of a hyphen or dash. In relation to the other characters making up a line of printed or written matter, the tilde may be used on, above, or below the line.
In phonetic transcriptions in linguistics, the tilde may be employed to indicate a nasal vowel (ã, õ). The symbol is used in some orthographies to show the palatalization of n; the Spanish alphabet, for example, has the letter ñ. In Greek the tilde is sometimes used as an alternate form of the circumflex, which originally indicated a rising-falling tone. In Lao and Vietnamese the symbol indicates a special tone. In, for example, comparative linguistics the tilde may be used to show the correspondence of units that are being compared. Another use of the tilde is the indication of the alternation of units.
In mathematical logic the tilde is the sign for equivalence in the Russell-Whitehead notation and the sign for the biconditional negation connective in the Hilbert notation.
The tilde is used in dictionary articles as a symbol standing for the word (or for part of the word) being defined.
In medieval manuscripts the tilde was employed to indicate the abbreviation of a word (see).