What is the name of the dot over a lowercase i or j?

The dot over a lowercase i or j is called a tittle.

A tittle is a small superscript dot that forms part of the lowercase letters i and j in many Latin-based writing systems. It is not normally treated as a separate punctuation mark; instead, it is a defining part of those letterforms. The term is uncommon in everyday speech, so many readers know the feature without knowing its name.

The word has a notable biblical association. In the King James Version of Matthew 5:18, “one jot or one tittle” refers to the smallest details of written law. The expression helped preserve the word in English even though modern writers usually just say “the dot on the i.”

A tittle can disappear or change when a letter takes another diacritic. In Turkish, dotted İ/i and dotless I/ı represent different letters and sounds. In many orthographies, the dot is replaced when an accent occupies the same position, though usage varies by language and writing system. The phrase “dot the i’s and cross the t’s” refers to careful attention to detail.