1794, "unfruitful, futile," from Latin otiosus "having leisure or ease, unoccupied, idle, not busy" (source of French oiseux, Spanish ocioso, Italian otioso), from otium "leisure, free time, freedom from business," a word of unknown origin. Meaning "at leisure, idle" is recorded from 1850. Compare Latin phrase otium cum dignitate "leisure with dignity." Earlier adjective in English was otious "at ease" (1610s), and Middle English had noun otiosity (late 15c.).