Lacking due respect or dutifulness:
— An undutiful son.

synonym: impious.

Roget 945: vicious; sinful; sinning etc. v.; wicked, iniquitous, immoral, unrighteous, wrong, criminal; naughty, incorrect; unduteous^†, undutiful.    unprincipled, lawless, disorderly, contra bonos mores [Lat.], indecorous, unseemly, improper; dissolute, profligate, scampish; unworthy; worthless; desertless^†; disgraceful, recreant; reprehensible, blameworthy, uncommendable; discreditable, disreputable; Sadistic.    base, sinister, scurvy, foul, gross, vile, black, grave, facinorous^†, felonious, nefarious, shameful, scandalous, infamous, villainous, of a deep dye, heinous; flagrant, flagitious; atrocious, incarnate, accursed.    Mephistophelian, satanic, diabolic, hellish, infernal, stygian, fiendlike^†, hell-born, demoniacal, devilish, fiendish.    miscreated^†, misbegotten; demoralized, corrupt, depraved.    evil-minded, evil-disposed; ill-conditioned; malevolent etc. 907; heartless, graceless, shameless, virtueless; abandoned, lost to virtue; unconscionable; sunk in iniquity, lost in iniquity, steeped in iniquity.    incorrigible, irreclaimable, obdurate, reprobate, past praying for; culpable, reprehensible etc. (guilty) 947.    unjustifiable; indefensible, inexcusable; inexpiable, unpardonable, irremissible^†.    weak, frail, lax, infirm, imperfect; indiscrete; demoralizing, degrading.    ... show more