An interior locution is a mystical concept used by various religions, including the Roman Catholic Church. In an interior locution, a person reportedly receives a set of (usually auditory) ideas, thoughts, or imaginations from an outside spiritual source. Interior locutions are most often reported during prayers. An interior locution is a form of private revelation, but is distinct from an apparition or religious vision because  no supernatural entity is reported as present during the interior locution.
In interior locutions, some people report quickly receiving large amounts of information. The determination of whether the locution was actually from another source or the person’s mind itself is often the subject of  controversy.
In two examples, the Vatican biographies of both Saint Teresa of Avila and Mother Teresa of Calcutta refer to their interior locutions, although Mother Teresa often preferred to remain private about them. Some visions of Jesus and Mary are classified as visions by the Vatican rather than locutions, e.g. those of Faustina Kowalska or Margaret Mary Alacoque.
Interior locutions sometimes lead to major new religious movements. For example the interior locutions reported by the Roman Catholic priest Father Stefano Gobbi on May 8th 1972 at the shrine of Our Lady of Fatima led to the formation of the Marian Movement of Priests in October 1972 or the messages received through inner word by Jakob Lorber and Gottfried Mayerhofer, which formed the so-called New Revelation of Jesus Christ and led to a worldwide movement counting thousands of adherents who are not organized in an institutionalized religious form.
 This is not considered so by many Catholics (and non-Catholics) who recognize that the receiving of locutions involves the presence and inspiration of God's Holy Spirit which is a supernatural entity.
 While controversial in some circles, interior locution (as understood among many Catholic disciplines) is not a matter of controversy and is clearly distinguished from personal thought by an awareness of the presence of the Holy Spirit which occurs simultaneously to the receipt of the locutions.
From the Latin locutio, speaking, speech, or discourse; and from loqui, to speak. Source
- Michael Freze, 1993, Voices, Visions, and Apparitions, OSV Publishing ISBN 0-87973-454-X