What is a prophet in Catholicism?

What is a prophet in Catholicism?

It was never man’s impulse, after all, that gave us prophecy; men gave it utterance, but they were men whom God had sanctified, carried away, as they spoke, by the Holy Spirit. - 2 Peter 1:21

For prophecy came not by the will of man at any time: but the holy men of God spoke, inspired by the Holy Ghost (cf. 2 Peter 1:21). The Prophets of the Old Testament were ever-so-conscious of this Divine mission. This continues in within the Catholic Church to our days. Nevertheless the Canon of the Scriptures closes with a prophetic book, the Apocalypse of St. John, which describes the struggles and the victories of the new kingdom while awaiting the return of its Chief at the consummation of all things. Catholic prophets nevertheless continued after the death of St. John the Evangelist.

See: Prophecy, Prophet, and Prophetess (Catholic Encyclopedia)

In the strictest sense God can work prophecy through whomever He chose to prophesy through, included may be angels, devils, men, women, children, heathens, or gentiles. Remember that Caiaphas prophesied about Christ’s pending crucifixion.

49 But one of them, named Caiphas, being the high priest that year, said to them: You know nothing.

50 Neither do you consider that it is expedient for you that one man should die for the people, and that the whole nation perish not.

51 And this he spoke not of himself: but being the high priest of that year, he prophesied that Jesus should die for the nation. - John 11:49-51

The Catholic Encyclopaedia explains who can have the ability to prophecy as follows:

Writing on the recipients of prophecy, Benedict XIV (Heroic Virtue, III, 144, 150) says: "The recipients of prophecy may be angels, devils, men, women, children, heathens, or gentiles; nor is it necessary that a man should be gifted with any particular disposition in order to receive the light of prophecy provided his intellect and senses be adapted for making manifest the things which God reveals to him. Though moral goodness is most profitable to a prophet, yet it is not necessary in order to obtain the gift of prophecy." He also tells us that the angels by their own natural penetration cannot know future events which are undermined and contingent or uncertain, neither can they know the secrets of the heart of another, whether man or angel. When therefore God reveals to an angel as the medium through which the future is made known to man, the angel also becomes a prophet. As to the Devil, the same author tells us that he cannot of his own natural knowledge foretell future events which are the proper objects of prophecy, yet God may make use of him for this purpose. Thus we read in the Gospel of St. Luke that when the Devil saw Jesus he fell down before Him and, crying out with a loud voice, said: "What have I to do with thee, Jesus, Son of the most high God?" (Luke 8:28). There are instances of women and children prophesying in Holy Scripture. Mary, the sister of Moses, is called a prophetess; Anna, the mother of Samuel, prophesied; Elizabeth, the mother of John the Baptist, by a Divine revelation recognized and confessed Mary as the Mother of God. Samuel and Daniel as boys prophesied; Balaam, a Gentile, foretold the advent of the Messias and the devastation of Assyria and Palestine. St. Thomas, in order to prove that the heathens were capable of prophecy, refers to the instance of the Sybils, who make clear mention of the mysteries of the Trinity, of the Incarnation of the Word, of the Life, Passion, and Resurrection of Christ. It is true that the Sibylline poems now extant became in course of time interpolated; but, as Benedict XIV remarks, this does not hinder much of them, especially what the early Fathers referred to, from being genuine and in no wise apocryphal. - Prophecy

God can enlighten individuals in several ways, but that does not necessarily make them a Prophet in the proper sense of the word. The Church rarely accords such titles to her children, including canonized saints. For example St. Hildegard of Bingen is known as the Sybil of the Rhine.

It is clear that Our Lady of Fatima foretold of many events that were about to pass to the children of Fatima. Books on the subject, almost all admitted that the predictions were from Mary the Mother of Jesus and that she communicated these predictions to Lucia da Santos. Yes Sr. Lucia revealed these to the world, but I do not believe that the Church views the Children of Fatima as prophets, but more as seers of Our Lady. Nevertheless I could see how, some may say so otherwise.

God can enlighten the human mind in any way he pleases. He often makes use of angelic ministry in prophetic communications, or He Himself may speak to the prophet and illuminate his mind. Again the supernatural light of prophecy may be conveyed to the intellect or through the senses or the imagination. Prophecy may take place even when the senses are suspended in ecstasy, but this in mystical terminology is called rapture. St. Thomas teaches that there is no suspension of the sense activities when anything is presented to the mind of the prophet through impressions of the senses, nor is it necessary when the mind is immediately enlightened that activity of the senses should be suspended; but it is necessary that this should be the case when the manifestation is made by imaginative forms, at least at the moment of the vision or of the hearing of the revelation, because the mind is then abstracted from external things in order to fix itself entirely on the object manifested to the imagination. In such a case a perfect judgment cannot be formed of the prophetic vision during the transport of the soul, because then the senses which are necessary for a right understanding of things cannot act, and it is only when a man comes to himself and awakens from the ecstasy that he can properly know and discern the nature of his vision. - Prophecy

Unfortunately the Apparitions of Fatima are a bone of contention for many Catholics. I believe that Pope Francis did in fact fulfill the demands of Our Lady on March 25th, 2022. See my question: Did Pope Francis' consecration of Russia and Ukraine fulfill all the demands that Mary requested at Fatima in 1917? The SSPX and Sedevacantists will naturally deny this.