Adult Characteristics Chart. A widely accepted definition of "adult learner" comes from Arthur Chickering, of the National Commission on Higher Education and the Adult Learner, which defines "Adult Learner" as an individual whose major role in . Aug 17, · Here are 20 defining characteristics of a true adult: Realizing that maturity is an ongoing process, not a state, and continuously striving for self improvement. Able to manage personal jealousy and feelings of envy. Has the ability .