Definition: Asylum applicant considered to be unaccompanied minor
International Migration and Asylum
Minor as defined in Article 2(i) of Directive 2004/83/EC i.e. below the age of 18, who arrives on the territory of the Member State unaccompanied by an adult responsible for them whether by law or custom, and for as long as they are not effectively taken into the care of such a person; it includes minors who are left unaccompanied after they have entered the territory of the Member States.
Eurostat, "Applications", General methodological information on International Migration and Asylum