tilde n.

c. 1300, "inscription, heading," from Old French title "title or chapter of a book; position; legal permit" (12c., Modern French titre, by dissimilation), and in part from Old English titul, both from Latin titulus "inscription, label, ticket, placard, heading; honorable appellation, title of honor," of unknown origin. Meaning "name of a book, play, etc." first recorded mid-14c. The sense of "name showing a person's rank" in English is first attested 1580s. Sports championship sense attested from 1913 (originally in lawn tennis), hence titlist (1913). A title role in theater is one which gives its name to the play.

"small stroke or point in writing," late 14c. (Wycliffe, in Matthew v.18), translating Latin apex in Late Latin sense of "accent mark over a vowel," which itself translates Greek keraia (literally "a little horn"), used by the Greek grammarians of the accents and diacritical points, in this case a Biblical translation of Hebrew qots, literally "thorn, prick," used of the little lines and projections by which the Hebrew letters of similar form differ from one another.

Wycliffe's word is borrowed from a specialized sense of Latin titulus (see title (n.)), which was used in Medieval Latin (and in Middle English and Old French) to indicate "a stroke over an abridged word to indicate letters missing" (and compare Provençal titule "the dot over -i-").

As apex was used by the Latin grammarians for the accent or mark over a long vowel, titulus and apex became to some extent synonymous; hence Wyclif's use of titil, titel to render L. apex [OED]

Compare tilde, which is the Spanish form of the same word.