tilde:

tilde (~) [1]: a diacritic symbol typically used to indicate a nasalized vowel. For example, ã represents 'nasalized a'. Also used as a diacritic on ñ and occasionally other consonants to indicate palatalization. [Spanish: tilde [1]]

tilde (~) [2]: a symbol which, when used by itself, indicates an alternation. For example, the alternation between "in-" and "im-" in words like "intolerable" and "impossible" can be written as "in- ~ im-"; one can also say that this is a case of "n ~ m". Compare slash [2] (/). [Spanish: tilde [2]]