This change is referred to as an ontological change, or a change in being itself.
In addition to making an ontological change, ordination also makes a legal change in a person's status in the Church. By ordination, a person becomes in canon law a "cleric." The word "cleric" is derived from the Greek word for "casting lots," a process of selection similar to drawing straws or rolling dice, because in Acts 1:26, Matthias is added to the 11 remaining apostles after lots are drawn to select the right person.
A cleric, or a sacred minister in the Church, is an ordained man who is permitted by the Church to exercise sacred ministry. A cleric is bound to certain obligations, among them is usually celibacy in the Latin Catholic Church, and he possesses certain rights, among them is the right to be appointed to pastoral leadership positions in the Church. Clerics have the right to be financially supported by the Church, and are bound by obedience to the pope and to local Church authorities.
While ordination can never be lost - no power on earth can erase the sacramental imprint of ordination - a person can lose the legal status of being a cleric- this is what is referred to as "laicization."
When a person loses the clerical state, he no longer has the right to exercise sacred ministry in the Church, except the extreme situation of encountering someone who is in immediate danger of death.
Someone who has lost the clerical state also no longer has the canonical right to be financially supported by the Church.