a young person who is developing into an adult
a young person who is developing into an adult : a young person who is going through adolescence
a young person, usually between the ages of 12 and 18, who is developing into an adult
Adolescent is just a fancy word for teenager — someone who is no longer a child but is not yet an adult. The word can also be used as an adjective. For example, a particular clothing line might be geared toward adolescent girls.