1. [adj]  not penitent or remorseful
2. [adj]  impervious to moral persuasion

IMPENITENT is a 10 letter word that starts with I.

1. \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.
   
   

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