Adolescent/ˌædəˈlesnt/ Definition 1 of 2Pro Tip 1/3Age Range Adolescents are typically 13 to 19 years old, covering the teenage period. He became more independent during his adolescent years. Pro Tip 2/3Puberty Reference Adolescents undergo puberty, experiencing significant physical and emotional changes. During his adolescent growth spurt, he outgrew all his clothes. Pro Tip 3/3Behavioral Context The term 'adolescent' can imply immaturity or inexperience in certain contexts. Her adolescent behavior at the meeting was unprofessional.