U+1E13 Latin Small Letter D with Circumflex Below

The Wikipedia has the following information about this codepoint:

The circumflex (◌̂) is a diacritic in the Latin and Greek scripts that is also used in the written forms of many languages and in various romanization and transcription schemes. It received its English name from Latin: circumflexus "bent around"—a translation of the Greek: περισπωμένη (perispōménē).

The circumflex in the Latin script is chevron-shaped (◌̂), while the Greek circumflex may be displayed either like a tilde (◌̃) or like an inverted breve (◌̑). For the most commonly encountered uses of the accent in the Latin alphabet, precomposed characters are available.

In English, the circumflex, like other diacritics, is sometimes retained on loanwords that used it in the original language (for example entrepôt, crème brûlée). In mathematics and statistics, the circumflex diacritic is sometimes used to denote a function and is called a hat operator.

A free-standing version of the circumflex symbol, ^, is encoded in ASCII and Unicode and has become known as caret and has acquired special uses, particularly in computing and mathematics. The original caret, ‸, is used in proofreading to indicate insertion.