Minor child

In law, a minor is a person under a certain age, usually the age of majority, which legally demarcates childhood from adulthood. The age of majority depends upon jurisdiction and application, but it is generally 18. Minor may also be used in contexts that are unconnected to the overall age of majority. For example, the drinking age in the United States is usually 21, and younger people are sometimes called minors in the context of alcohol law, even if they are at least 18. The term underage often refers to those under the age of majority, but it may also refer to persons under a certain age limit, such as the drinking age, smoking age, age of consent, marriageable age, driving age, voting age, etc. Such age limits are often different from the age of majority.

The concept of minor is not sharply defined in most jurisdictions. The ages of criminal responsibility and consent, the age at which school attendance is no longer compulsory, the age at which legally binding contracts can be entered into, and so on may be different from one another.

In many countries, including Australia, India, Philippines, Brazil, Croatia, and Colombia, a minor is defined as a person under the age of 18. In the United States, where the age of majority is set by the individual states, minor usually refers to someone under the age of 18 but can, in some states, be used in certain areas (such as casino gambling, handgun ownership and the consuming of alcohol) to define someone under the age of 21. In the criminal justice system in some places, "minor" is not entirely consistent, as a minor may be tried and punished for a crime either as a "juvenile" or, usually only for "extremely serious crimes" such as murder, as an "adult".

...
Wikipedia