"to make neat, set in order," 1821, from tidy, adj.. Related: Tidied; tidying.

mid-13c., "in good condition, healthy," probably originally "in season, timely, opportune, excellent" (though this sense is not attested until mid-14c.), from tide, n. in the sense of "season, time" + -y(2). Of persons, "of neat and orderly habits," from 1706. Similar formation in Old High German zitig, German zeitig, Dutch tijdig, Danish tidig "timely," Old English tidlic "temporal," also "timely, seasonable."