Canada:
“Anyone reported to police or by police as someone whose whereabouts are unknown, whatever the circumstances of their disappearance, and they are considered missing until located. A missing person under the age of 18 is classified as a missing child. In the case of a missing child, they are considered missing if they are no longer in the care or control of their legal guardian and have not been removed by law, and they are considered missing until returned to appropriate care and control.”
Greece:
“Any child, under 18 years of age, whose whereabouts are unknown by his/her custodial parent(s) or legal guardian(s).”
India:
“A missing child is a child, whose whereabouts are not known to the parents, legal guardian or any other person or institution legally entrusted with the custody of the child, whatever may be the circumstances or causes of disappearance, and shall be considered missing and in need of care and protection until located or his safety and well-being established.”
Juvenile Justice (Care and Protection of Children) Act, Article 92 (G.S.R. 898, 21 Sept. 2016)
South Korea:
“Article 2:
1. The term ‘child, etc’ means any of the following persons:
a. A child under the age of 14 at the time he/she goes missing;
b. A person with an intellectual, autistic or mental disability, among persons with disabilities.
2. The term ‘Missing child, etc’ means any child, etc. separated from his/her custodian due to any cause, such as abduction, enticement, desertion, accident, leaving home or getting lost.”
Protection and Support for Missing Children Act, Article 2 (Act No.11048, 15 Sept. 2011)