conversloconversion; viz., the work of the Holy Spirit according to which the intellect and the will of the sinner are turned toward God in contrition and faith.Conversion can be distinguished into:

(1) conversio passiva sive habitualis, passive or habitual conversion, commonly called regeneration (regeneratio), in which the will, passively, without any motion of its own, receives by grace alone the habit or disposition (habitus, q.v.) toward repentance and new life in Christ. Because the work of the conversio passivabegins in God and passes to the human subject, it is also called conversio transitiva, transitive conversion, a conversion that passes over from one being to another.

(2) Conversio activa sive actualis, active or actual conversion, commonly called conversion (conversio) without modifier, in which the regenerated will actually and actively turns toward God; i.e., the human side of conversion, the actual repentance or metanoia. Because the conversio activa is confined to the human subject, it is sometimes called conversio intransitiva, intransitive conversion, or conversion that does not pass over from one being to another. Conversio activa is sometimes also called regeneratio secunda, a second or further regeneration, belonging to the renovation (renovatio, q.v.) of the individual.

The scholastics also define conversion in relation to its termini, or limits. The terminus a quo (q.v.) of conversion in a formal sense is sin itself, sin as such, while in an objective sense it is the specific objects of or reasons for sinning peculiar to the individual sinner. The terminus ad quem (q.v.) of conversion, formally considered, is faith in Christ; objectively considered, God, to whom the repentant return in and through Christ. The orthodox deny the concept of a homo renascens (q.v.), or man in process of being reborn in conversion, and therefore all notion of a middle condition (status medius) between the two termini of conversion. In other words, conversion is not a process. Thus conversio transitiva is immediately effective as conversio intransitivaconversio habitualisimmediately resultant in conversio actualis. The divine work and the turning of the human heart are inseparable and are distinguished only in terms of the subject of the operation.

Source:
Richard Muller. Dictionary of Latin and Greek Theological Terms: Drawn Principally from Protestant Scholastic Theology (p. 83).