The dot over the letter "i" is called a tittle.
A tittle is a mark of punctuation used in the English language over letters like “i” and “j” in lowercase form. A tittle can also include marks like the tilde (~) and the umlaut, which is just two dots, though this can depend on whom you ask, as some debate on this topic.
Accent marks aren’t included in the definition of tittle, but not all letters with accents are without tittles as well, such as the ogonek (seen with letters like this one: Äaut;...). These are probably rare to many of our readers because they're symbols used mostly in non-Romance languages (languages other than ones such as Portuguese, English, Spanish, Italian, Latin, and French).
Some letters can use both ogoneks and tittles, but never in the English language, as well as most Romance languages. Other odd names for symbols: -Interrobang: ?! -Guillemet: > -Pilcrow: ¶ -Solidus: / -Circumflex: -Caret: ^