Wiktionary
n. 1 The name of a natural person recognized on official records, especially as recorded on a birth certificate or as allowed to changed by legal process. 2 The name of an organisation as indicated in its founding documents, as subsequently changed by legal process.
Wikipedia
Legal name is the name that identifies a person for legal, administrative and other official purposes. A person's first legal name generally is the name of the person that was given for the purpose of registration of the birth and which then appears on a birth certificate (see birth name), but may change subsequently. Most jurisdictions require the use of a legal name for all legal and administrative purposes, and some jurisdictions permit or require a name change to be recorded at marriage. The legal name may need to be used on various government issued documents (e.g., a court order). The term is also used when an individual changes their first or full name, typically after reaching a certain legal age (usually eighteen or over, though it can be as low as fourteen in several European nations).
A person's legal name typically is the same as their personal name, comprising a given name and a family name. The order varies according to culture and country. There are also country-by-country differences on changes of legal names by marriage. (See married name.)
Most countries require by law the registration of a name for newborn children, and some can refuse registration of "undesirable" names. In 1991, a Swedish couple refused to give their newborn a legal name, in protest of existing naming laws. In 1996, they were fined for not registering a name for their child for five years, after they unsuccessfully tried to register the child's name as Brfxxccxxmnpcccclllmmnprxvclmnckssqlbb11116, and then as "A".
The legal name of a business is the name under which the business conducts its operations.
Usage examples of "legal name".
I also have a daughter, yes, she is older than my son, she is twenty-four, and her legal name is Mindy Dilman.
If she'd used the courts of Kansas for a legal name change, there was no record of it.
He'd picked up Pepper at a young age, and had vigorously asserted it as his legal name.
A police detective, good at providing accurate descriptions, would have described Charles Zolar, legal name Charles Oxley, as a con man who did not look like a con man.