We’ll be honest, we’ve never actually wondered what the dot over the i or j (in lowercase, of course) was called. But if you’ve been curious, kudos to you for noticing the small things! And to answer your question, it’s called a “tittle.”
Why do we have marks over letters and characters?
Many languages have what we call diacritic marks over a character in order to change its sound or meaning. But English only has two letters with a diacritic – lowercase i and j. They’re always there and don’t change anything about the sound or meaning of the letter (in English, at least).
According to Dictionary.com: “The small distinguishing mark you see over a lowercase i and a lowercase j is called a tittle—an interesting name that looks like a portmanteau (combination) of tiny and little, and refers to a small point or stroke in writing and printing. Generally, a diacritic dot such as a tittle is also referred to as a glyph, a mark that adds meaning to the written letter. However, in regards to i and j, the removal of the mark is still likely to be read as I or J; as such, these are not true examples of a glyph.”
Why is the dot over the i and j called a tittle?
Who comes up with these things anyway?
Well, tittle comes from the Latin word “titulus.” A titulus is an inscription or heading. The word appeared for the first time in the 11th century as monks were copying manuscripts from the ancient world. Back in that day, handwriting was very different, and letters could easily get confused or blend together. As you may have guessed, i and j posed particular problem. That’s why copiers needed to come up with a diacritic to distinguish them from other letters.
It wasn’t until the 1400s when the printing press and typefaces were invented that the diacritical mark turned into just a small dot above each letter.
In other words, they’re simply a relic of a time when everything was handwritten. — WTF fun facts
Source: “What’s The Name For The Dot Over “i” And “j”?” — Dictionary.com