Globally, there are at least two relevant definitions in play per Wikipedia:
A child (pl. children) is a human being between the stages of birth and puberty,[1][2] or between the developmental period of infancy and puberty.[3] It may also refer to an unborn human being.[4][5] In English-speaking countries, the legal definition of child generally refers to a minor, in this case as a person younger than the local age of majority (there are exceptions like, for example, the consume and purchase of alcoholic beverage even after said age of majority[6]), regardless of their physical, mental and sexual development as biological adults.[1][7][8]
It seems reasonable to request clarification as to which definition of child is being used.