U+01D4 Latin Small Letter U with Caron

The Wikipedia has the following information about this codepoint:

A caron is a diacritic mark (◌̌) commonly placed over certain letters in the orthography of some languages to indicate a change of the related letter's pronunciation.

The symbol is common in the Baltic, Slavic, Finnic, Samic and Berber languages.

The use of the caron differs according to the orthographic rules of a language. In most Slavic and other European languages it indicates present or historical palatalization (e → ě; [e] → [ʲe]), iotation, or postalveolar articulation (c → č; [ts] → [tʃ]). In Salishan languages, it often represents a uvular consonant (x → x̌; [x] → [χ]). When placed over vowel symbols, the caron can indicate a contour tone, for instance the falling and then rising tone in the Pinyin romanization of Mandarin Chinese. It is also used to decorate symbols in mathematics, where it is often pronounced ("check").

The caron is shaped approximately like a small letter "v". For serif typefaces, the caron generally has one of two forms: either symmetrical, essentially identical to a rotated circumflex; or with the left stroke thicker than the right, like the usual serif form of the letter "v" (but without serifs). The latter form is often preferred by Czech designers for use in Czech, while for other uses the symmetrical form tends to predominate, as it does also among sans-serif fonts.

The caron is not to be confused with the breve (◌̆), which has a curved bottom, while the caron is pointed (see illustration).