Dot Above

Its meaning depends on the notation around it. In Bopomofo, a phonetic notation used to write Mandarin syllables, ˙ marks the light, or neutral, tone. Taiwan’s Ministry of Education places it above the Bopomofo symbols in vertical text and before them in horizontal text.

A lone ˙ does not identify which notation is intended. The surrounding letters, formula, or pronunciation notes tell you whether it marks a tone, a sound, or a mathematical operation.

Where did the overdot come from?

A surviving Syriac system of vowel marking used dots above and below vowels by at least the fifth century. Syriac, an Aramaic language, used the dots to help readers distinguish words with different vowels while reading important texts aloud. Syriac vowel marking influenced Arabic dot vocalization; the Tiberian Hebrew tradition used its own dot placement.

In the early 15th century, Czech writing used punctus rotundus, a round dot, over softened consonants before the caron (ˇ), a small wedge-shaped accent, took over that role. Old Irish, an earlier form of Irish, used an overdot for lenition, the weakening of a consonant; over f it could signal that the letter was silent. In mathematics, an overdot above a variable marks its derivative with respect to time—how quickly that quantity changes.

Why won’t ˙ sit on a letter?

Because ˙ takes its own position in the text. It is a spacing character, so it does not attach to a nearby letter. Its gap and height can shift with the font. The combining dot above (◌̇) is the mark used when the dot must attach to a letter.