Biologically, an adult is a human or other organism that has reached sexual maturity. In human context, the term adult additionally has meanings associated with social and legal concepts. In contrast to a "minor", a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, and responsible. The typical age of attaining adulthood is 18, although definition may vary by legal rights and country.
Adult education is a practice in which adults engage in systematic and sustained self-educating activities in order to gain new forms of knowledge, skills, attitudes, or values. It can mean any form of learning adults engage in beyond traditional schooling, encompassing basic literacy to personal fulfillment as a lifelong learner.
Education is the process of facilitating learning, or the acquisition of knowledge, skills, values, beliefs, and habits. Educational methods include storytelling, discussion, teaching, training, and directed research. Education frequently takes place under the guidance of educators, but learners may also educate themselves. Education can take place in formal or informal settings and any experience that has a formative effect on the way one thinks, feels, or acts may be considered educational. The methodology of teaching is called pedagogy.
The Self-Educated are marked by stubborn peculiarities.
Isaac D'Israeli, Literary Character, Chapter VI.
I hope we still have some bright twelve-year-olds who are interested in science. We must be careful not to discourage our twelve-year-olds by making them waste the best years of their lives on preparing for examinations.
Freeman Dyson, “Butterflies and Superstrings” in Timothy Ferris (ed.) The World Treasury of Physics, Astronomy, and Mathematics (p. 135)
By education most have been misled.
John Dryden, The Hind and Panther, Part III, line 389.