the years of a person’s life when they are between 13 and 19 years old She began writing poetry in her teens. to be in your early/late teens See related entries: Youth Word Origin late 17th cent.: plural of teen, independent usage of -teen.Extra examples He didn’t want to share a room with his brother once he reached his teens. His parents divorced during his teens. She’s had skin problems since her teens. a girl in her early teens An eyewitness described a boy in his mid to late teens wearing a dark jacket. She began writing poetry in her teens.