(Latin: conterere, to bruise)
Sorrow for, and detestation of, one's past actual sins, with the purpose not to sin in future.
Contrition is the principal act of the virtue of penance, and an essential element of the Sacrament of Penance.
To be conducive to salvation and to justification contrition must be based on a supernatural motive and must extend to all mortal sins.
Contrition is called perfect when its motive is love for God.
Such contrition procures the remission of sins without the actual reception of a sacrament, though it must contain, at least implicitly, the intention of receiving either Baptism (in the case of an unbaptized person), or Penance (in the case of one already baptized).
Contrition proceeding from any other supernatural motive than Divine charity is called imperfect contrition, or attrition, and constitutes a sufficient disposition for the remission of sins, through the actual reception of Baptism or of Penance.
New Catholic Dictionary