Also found in: Thesaurus, Legal, Encyclopedia, Wikipedia.pi·ous (pī′əs)adj.1.a. Earnestly compliant in the observance of religion; reverent or devout: a pious nun.b. Showing or characterized by religious devotion: pious observance.c. Expressive of or used in religious devotion; devotional: pious readings.2.a. Done for the benefit of others or with the intention of encouraging good: practicers of the noble lie and thepious fraud.b. Sincere but wishful or far-fetched: a pious hope that the new method will work.3. Self-righteous or sanctimonious: pious denunciations of sexual harassment.4. Archaic Professing or exhibiting traditional morality; dutiful.