Eira Monstad Oxford English Dictionnary confirms 'tittle' although any sign, such as the Spanish tilde (same origin) or the French accents or German Umlauts, part of a letter can be considered a tittle
Kurk Knight No, it is not. A tittle is a distinguishing mark, purely visual to help distinguishing a letter that may otherwise blend in with other letters. Typically seen as the dot over the i. If there is a diacritic, the tittle is simply dropped, because it is unimportant. In this case, we're seeing a diacritic (the acute accent, to be specific) - a pun on the typical "Starbucks French" pronunciation of the "Grande" size (which is just Large with a fancy name to make it sound hip).
Kurk Knight Tittles and tildes are different things. Anyway, Wikipedia has excellent articles on tittles versus diacritics, so I won't spend my time repeating typology trivia here. The most important distiction - tittles do not change the pronunciation, while diacritics typically do. If the mark seen in this drawing did not change the pronunciation, the pun would disappear.
Eira Monstad strait off the first line of WIKI (your choice)" A tittle is a small distinguishing mark, such as a diacritic"
so it IS a diacritic so dont act all superior when someone simply corrects you