a juvenile between the onset of puberty and maturity
"The adolescent teenager struggled to balance his growing independence with the responsibilities of home life."
A person who is in adolescence; someone who has reached puberty but is not yet an adult.
"The adolescent struggled to balance his growing independence with the expectations of his parents."
In plain English: An adolescent is someone who has gone through puberty and is growing into adulthood but isn't quite an adult yet.
"The restless adolescent spent his afternoon staring out the window instead of doing homework."
displaying or suggesting a lack of maturity
"adolescent insecurity"
"jejune responses to our problems"
"their behavior was juvenile"
"puerile jokes"
Of, relating to, or at the age of adolescence; at the stage between being a child and an adult
"The adolescent teenager struggled to balance her growing independence with the responsibilities of family life."
In plain English: Adolescent means something that is growing up and not yet fully developed into an adult form.
"The adolescent boy struggled to open his soda can."
Usage: Use "adolescent" as both an adjective describing teenage years and a noun referring to a teenager, though it often carries a connotation of immaturity or rebelliousness that the neutral term "teenager" lacks. Avoid using this word when you simply need a factual descriptor for age without implying behavioral traits associated with growing up.
The word entered English around 1440 from Middle French and Latin, originally describing the process of growing into adulthood. It was not until 1785 that it began to be used as an adjective specifically for a young person in this stage of life.