Meaning

adjective neat and tidy

originBack-formation from unruly, or perhaps a continuation of Middle English rewly, ruly, reuli (“subject to a religious rule, regular”), equivalent to rule + -ly, rule + -y; or perhaps from Old French rulé, reulé, rieulé (“ruled”), past participle of rieuler (“to rule”). More at rule.

Etymology from Wiktionary, CC BY-SA 3.0