noun Etymology: Spanish, from Medieval Latin titulus tittle Date: circa 1864 a mark ˜ placed especially over the letter n (as in Spanish señor sir) to denote the sound \\nʸ\\ or over vowels (as in Portuguese irmã sister) to indicate nasality,
2. the mark tilde used to indicate negation in logic and the geometric relation “is similar to” in mathematics, the mark tilde used to indicate an approximate value
