minor who arrives on the territory of the Member States unaccompanied by an adult responsible for him or her whether by law or by the practice of the Member State concerned, and for as long as he or she is not effectively taken into the care of such a person; it includes a minor who is left unaccompanied after he or she has entered the territory of the Member States;

Based on Article 2(e) RCD recast and Article 2(m) APD recast, referring to Article 2(l) QD recast.