A breve is the diacritic mark ◌̆, shaped like the bottom half of a circle. As used in Ancient Greek, it is also called brachy, βραχύ. It resembles the caron but is rounded, in contrast to the angular tip of the caron. In many forms of Latin, ◌̆ is used for a shorter, softer variant of a vowel, such as "Ĭ", where the sound is nearly identical to the English /i/.

A diacritic is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek διακριτικός, from διακρίνω. The word diacritic is a noun, though it is sometimes used in an attributive sense, whereas diacritical is only an adjective. Some diacritics, such as the acute ⟨á⟩, grave ⟨à⟩, and circumflex ⟨â⟩, are often called accents. Diacritics may appear above or below a letter or in some other position such as within the letter or between two letters.