Source : Webster's Revised Unabridged Dictionary (1913)

Impenitent \Im*pen"i*tent\, a. [L. impaenitens; pref. im- not +
   paenitens penitens: cf. F. imp['e]nitent. See {Penitent}.]
   Not penitent; not repenting of sin; not contrite; of a hard
   heart. ``They . . . died impenitent.'' --Milton. ``A careless
   and impenitent heart.'' --Bp. Hall.

Impenitent \Im*pen"i*tent\, n.
   One who is not penitent. [R.]

Source : WordNet®

impenitent
     adj 1: not penitent or remorseful [syn: {unrepentant}, {unremorseful}]
            [ant: {penitent}, {penitent}]
     2: impervious to moral persuasion