'Tilde' definitions:

Definition of 'tilde'

From: WordNet
noun
A diacritical mark (~) placed over the letter n in Spanish to indicate a palatal nasal sound or over a vowel in Portuguese to indicate nasalization

Definition of 'Tilde'

From: GCIDE
  • Tilde \Til"de\, n. [Sp., fr. L. titulus a superscription, title, token, sign. See Title, n.] The accentual mark placed over n, and sometimes over l, in Spanish words [thus, [~n], [~l]], indicating that, in pronunciation, the sound of the following vowel is to be preceded by that of the initial, or consonantal, y. [1913 Webster]