“apostate: a person who renounces a religious or political belief or principle. “
But right here on FR, catholics tell people that once a catholic, always a catholic. This, even when they are apostate.
Reception of the Sacraments of Baptism and of Holy Orders result in an ontological change, an indelible mark upon the soul.
If an apostate who abandoned the Church were to return to the practice of the Catholic Faith, he wouldn't need to be re-baptized.