orderly (adj.)

"arranged in order," 1570s, from order (n.) + -ly (1).

orderly (adv.)

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

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.).