orderly (adv.)

late 15c., "in due order, duly, properly," from order + -ly (2).

"military attendant who carries orders," 1781, short for orderly corporal, etc. Extended 1809 to an attendant at a hospital (originally a military hospital) charged with keeping things clean and in order, from orderly (adj.) in the military sense of "of or pertaining to communication or execution of orders" (1723).

1570s, "arranged in order," from order (n.) + -ly (1). Meaning "observant of rule or discipline, not unruly" is from 1590s. Related: Orderliness.