adjective
1.
lacking reverence for holy or sacred matters
made impious remarks about the church
Synonyms: irreverent, irreverential, profane, ungodly, unhallowed, unholy
Related Word: godless, iconoclastic, irreligious, sacrilegious, scandalous, undevout
Contrasted words: devout, godly, religious, spiritual
Antonyms: pious
2.
lacking due respect (as toward one's parents)
an impious son
Synonyms: unduteous, undutiful
Related Word: disobedient, froward, unfaithful, wayward; contrary, perverse, wrongheaded
Contrasted words: duteous, dutiful