orderly (adv.)
late 15c., "in due order," from order + -ly (2).
orderly (adj.)
"arranged in order," 1570s, from order (n.) + -ly (1).
orderly (n.)
"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 in order and clean. See orderly (adj.).