A matronymic is a personal name or a parental name based on the given name of one's mother, grandmother, or any female ancestor. It is the female equivalent of a patronymic. Around the world, matronymic surnames are far less common than patronymic surnames. In some cultures in the past, matronymic last names were often given to children of unwed mothers. Additionally, if a woman was especially well known or powerful, her descendants might adopt a matronym based on her name. A matronymic is a derived name, as compared to a matriname, which is an inherited name from a mother's side of the family, and which is unchanged.

The word matronymic is first attested in English in 1794 and originates in the Greek μήτηρ mētēr "mother" (GEN μητρός mētros whence the combining form μητρo- mētro-), ὄνυμα onyma, a variant form of ὄνομα onoma "name", and the suffix -ικός -ikos, which was originally used to form adjectives with the sense "pertaining to" (thus "pertaining to the mother's name"). The Greek word μητρωνυμικός mētrōnymikos was then borrowed into Latin in a partially Latinised form (Greek mētēr, dialectally mātēr, corresponds to Latin mater), as matronomicus. These words were a source for coining the English matronymic as the female counterpart to patronymic (first attested in English in 1612). Whereas the Oxford English Dictionary records an English noun patronym in free variation with the noun patronymic, it does not, however, record a corresponding noun matronym.

More rarely, English writers use forms based wholly on Greek: the noun metronym (first attested in 1904); and the noun and adjective metronymic (first attested in 1868). These are, for example, the forms used in the 2016 The Oxford Dictionary of Family Names in Britain and Ireland. Speakers are in practice likely to use female-line name, or name of "his/her mother" to be both specific and avoid use of technical terms.

Some matrilineal communities in South and North-East India, like the Nairs, Bunts and Khasi, have family names which are inherited from their mother. Matronymic names are common in Kerala. Daughters take the names of their mothers as the second part of their name.^{[citation needed]}

Some Minangkabau people use this naming system; many people, however, have no surname at all. People of Enggano Island also use a matronymic system. They also have family name/surname (marga).

In July 2023, the Constitutional Court of Kyrgyzstan decided that adults may have the right to use a matronymic instead of the traditional patronymic on their official documents. After pushback from conservative groups, the court reversed its decision in November.

The book Kitāb man nusiba ilá ummihi min al-shu‘arā’ (the book of poets who are named with the lineage of their mothers) by the 9th-century author Muḥammad ibn Ḥabīb is a study of the matronymics of Arabic poets. There exist other examples of matronymics in historical Arabic.

While most Mongolian names today are patronymic, some Mongolians are known to be matronymic. This could be due to, for example, an absence of the father such as in the case of Punsalmaagiin Ochirbat, the first elected president of Mongolia.