In Catholicism, what does "mystical" mean?

St. Alphonsus di Liguori's The Glories of Mary explains all the parts of the Litany of Loretto. Regarding the "Rosa Mystica," he writes:

"Rosa mystica:" Mystical rose. It is said of Mary in the holy Canticles that she was the inclosed garden of God: "Hortus conclusus soror mea sponsa."* And St. Bernard, explaining this passage, says that the Lord planted in this garden all the flowers that adorn the Church, and among others, the violet of humility, the lily of purity, and the rose of charity. The rose is red; and therefore Mary is called the rose, according to the Idiot, on account of the ardent charity with which her heart was always inflamed towards God and towards us.† And where can we find an advocate who is more occupied with our salvation and who loves us more than Mary? We acknowledge that one alone in heaven is solicitous for us, as St Augustine says of her.‡ Oh my dear mother, if I could love thee as thou lovest me! I will not, however, fail of doing what I can to honor and love thee; my sweet Lady, obtain for me the grace to be faithful to thee.

^{* iv. 12.
† Rosa rubicunda per Dei et proximi charitatem; Dei ignens calor charitatem denotat.
‡ Unam solam in cœlis fatemur esse solicitam.}

1. Theol.

a. Having a spiritual character or significance by virtue of a connection or union with God which transcends human understanding.

2.

b. Relating to or designating a hidden, symbolic, or spiritual meaning (or some aspect of this) underlying the literal meaning of a passage of Scripture. Cf. allegorical adj., anagogical adj., tropological adj.

a. More generally: mysterious, enigmatic, obscure, esoteric; of hidden meaning or nature; having an unknown or mysterious origin or influence. Cf. mystic n. 2.

b. Of a person: obscure in speech, mysterious in behaviour; versed or apparently initiated in occult or esoteric knowledge. Obs.

3. Relating to or dealing with spiritual or transcendental matters, esp. communion of the soul with God or some higher spiritual power; concerned with spiritual mystery, religious awe, etc. Also: relating to or characteristic of mystics or mysticism. Cf. mystic adj. 5, mystical theology n. at Special uses.

4. Of or relating to mysterious or occult rites or practices. Cf. mystic n. 3. Also in extended use.

5. Secret, concealed; unconfessed. Obs.

mystical theology n. the branch of theology that deals with the attainment of direct communion of the soul with God.

For a good overview of mystical theology, see this by Fr. Garrigou-Lagrange, O.P.

MYSTICAL BODY

The Catholic Church established by Christ as an extension and continuation of the Incarnation.

In the words of Pius XII, "If we would define and describe the true Church of Jesus Christ -- which is the one, holy, Catholic, apostolic Roman Church -- we shall find nothing more noble, more sublime, or more divine than the expression 'the Mystical Body of Jesus Christ' -- an expression that flows spontaneously from the repeated teaching of the sacred Scriptures and the holy Fathers."

The term "body," when referring to the Church, derives its meaning from the analogy used by St. Paul, where he speaks of Christians: "You are the Body of Christ, member for member" (I Corinthians 12:27), and of Christ: "the Head of His Body, the Church" (Colossians 1:18).

Corollary to being a body, the Church must have a multiplicity of discernible members because the possession of parts is an essential feature of anything bodily. And just as a natural body is formed of different organs with different functions arranged in due order, so the Church is bound together by the combination of structurally united parts, and has a variety of members that are reciprocally dependent. Another name for this interdependence is the hierarchy, with its graded levels of orders and jurisdiction, of superiors and subjects, beginning with the Sovereign Pontiff and terminating in the laity.

The body (soma) that St. Paul identifies with the Church is a living reality, and like every organism requires suitable means to enter into life, to grow and mature and prosper according to its nature. Similarly in the Catholic Church, the sacraments are available for every spiritual need and circumstance of human life.

Moreover, the Roman Catholic Church regards herself as the Body of Christ. He was the originator of the Church by his preaching and choice of the Apostles to carry on his work, by his death on the Cross when he merited the graces to be channeled through the Mystical Body, and by the descent of the Holy Spirit, whom he sent on Pentecost. He continues to rule the Church from within by supernatural means that are permanent and constantly active within the members.

The Church is called Mystical because she is a mystery, which God revealed to be true but whose inner essence must be accepted on faith and without full comprehension by the mind. Otherwise than in other societies, the end or purpose of the church is not temporal or earthly but heavenly and eternal; its spiritual bond is the will of God; incorporation in the Church effects a profound internal change in the members; and the whole reality is called supernatural because it leads to the destiny of seeing God in the beatific vision after death. But the Roman Catholic Church is mainly said to be the Mystical Body of Christ because it is sacramental. The Church is the great sacrament of the New Law, instituted by Christ for the communication of invisible grace to the whole world.

MYSTICAL INTERPRETATION

The explanation of some biblical person, object, or occurrence in the past as having a divinely intended meaning or function in the future. Thus Adam prefigured Christ, the Passover anticipated the Cross and the Eucharist, and the destruction of Jerusalem in the first century of the Christian era symbolized the end of the world. To be valid, the basis for the interpretation must be found in Scripture or sacred tradition.

MYSTICAL ROSE

A traditional title given to Mary, and an invocation in the Litany of Loreto. As the rose is considered the queen of flowers, so Mary in invoked as Queen of All Saints. As described by sacred writers, she is the "mystical rose without thorn," the "rose of paradise," and the "rose bringing salvation to all who call upon her."

MYSTICAL THEOLOGY

The science of the spiritual life, with stress on the operation of divine grace. It deals with the higher forms of mental prayer and with such extraordinary phenomena as are recorded in the lives of the saints. It is the science of the study of the mystic states. It is commonly distinguished from ascetical theology, which emphasizes free co-operation with and predisposition for divine grace.

MYSTICAL UNION

The union of a soul with God in deep contemplation. It is characterized by a deep awareness of the divine presence, and has a variety of grades, not necessarily successive, but distinguished by spiritual writers. They are: the two nights of the soul (senses and spirit) before mystical union, the prayer of quiet, the full union, ecstasy, and spiritual marriage or transforming union.