late 15c. (Caxton), "destroy or derange the order of, throw into confusion," from dis- "not" (see dis-) + order (v.). Replaced earlier disordeine (mid-14c.), from Old French desordainer, from Medieval Latin disordinare "throw into disorder," from Latin dis- + ordinare "to order, regulate," from ordo (genitive ordinis) "row, rank, series, arrangement" (see order (n.)). Related: Disordered; disordering.
1831, "pertaining to origins," coined by Carlyle as if from Greek genetikos from genesis "origin" (see genesis). Darwin used it biologically as "resulting from common origin" (1859); modern sense of "pertaining to genetics or genes" is from 1908 (see gene). Related: Genetically. Genetical is attested from 1650s as "pertaining to origins."
1520s, "lack of regular arrangement;" 1530s, "tumult, disturbance of the peace;" from disorder (v.). Meaning "an ailment, a disturbance of the body or mind" is by 1704.
(abbreviated ADD), introduced as a diagnosis in the third edition of the "Diagnostic and Statistical Manual of Mental Disorders" (1980), from attention in the "power of mental concentration" sense. Expanded to attention deficit hyperactivity disorder ("the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone;" ADHD) in DSM-III (1987).
genetic disorder causing developmental and intellectual delays, 1961, from J.L.H. Down (1828-1896), English physician; chosen as a less racist name for the condition than earlier mongolism.
1959, from clone (n.). Extension to genetic duplication of animals and human beings is from 1970. Related: Cloned; cloning.