Breve

◌̆
Breve
Some typefaces differentiate Cyrillic style (top) and Latin style breve (bottom)
Some typefaces differentiate Cyrillic style (top) and Latin style breve (bottom)

A breve (/ˈbrv/ BREEV, less often /ˈbrɛv/ BREV, neuter form of the Latin brevis "short, brief") 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 (◌̌, the wedge or háček in Czech, mäkčeň in Slovak) 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/. (See: Latin IPA)

Breve vs. caron
Breve Ă ă Ĕ ĕ Ĭ ĭ Ŏ ŏ Ŭ ŭ Y̆ y̆
Caron Ǎ ǎ Ě ě Ǐ ǐ Ǒ ǒ Ǔ ǔ Y̌ y̌