The two-word term biological adult stresses or clarifies that the original definition, based on physical maturity, is being used.
In humans, puberty on average begins around 10–11 years of age for girls and 11–12 years of age for boys, though this will vary from person to person.
Conversely, one may legally be an adult but possess none of the maturity and responsibility that may define an adult character.
After the social construct of adolescence was created, adulthood split into two forms: biological adulthood and social adulthood.
Thus, there are now two primary forms of adults: biological adults (people who have attained reproductive ability, are fertile, or who evidence secondary sex characteristics) and social adults (people who are recognized by their culture or law as being adults).
There may be distinction between commercially and socially enabling.
Sometimes there is the requirement of supervision by a legal guardian, or just by an adult.
Biologically, an adult is a human or other organism that has reached sexual maturity.