Dictionary of Scholastic Terminology

Work in Progress

This dictionary is incomplete, but will be updated until finished.


Metaphysics: the study of the so-called first or basic principles; the study of the nature of reality itself. Some important sub-studies are:

  1. Ontology: metaphysics dealing with the nature of how things exist, and the degree to which they do.
  2. Teleology: metaphysics dealing with the purpose (also called “final end” or “telos”) of a thing.
  3. Cosmology: metaphysics dealing with the origin, fundamental structure, nature, and dynamics of the cosmos.

Scholasticism: the system of Catholic theology and philosophy taught in medieval European universities, grounded in the notion that some truths are attainable via reason alone, others via faith alone, (meaning, while Revelation was necessary for our Salvation, non-Christians could contribute to truth by way of reason) and having a strong emphasis on Tradition and dogma. In a modern context, Scholasticism is very nearly, if not actually, the same as Thomism.

Thomism: the form of Scholasticism associated with St Thomas Aquinas, which is regarded as the norm of theology and philosophy in the Western Church. Thomism has largely become synonymous with Scholasticism.

The Philosopher: the title given by Aquinas to Aristotle.

The Master: the title [from the Latin “magister,” which dynamically translated is “teacher,” but literally translated is “master”] given by Aquinas to Peter Lombard, author of The Sentences, the dominant theological text of the time.

The Commentator: the title given by Aquinas to Averroes, who wrote commentaries on Aristotle.

The Theologian: the title given by Aquinas to St Augustine of Hippo.

The Jurist: the title given by Aquinas to Ulpian the Roman Jurist.

The Apostle: the title given by Aquinas to St Paul the Apostle.

Dionysius: known to modern scholars as Pseudo-Dionysius.

Act: an existing or actual state.

Potency: a potential or possible state.

Form: the immaterial principle or aspects of a thing which determines that which the thing is.

Matter: the physical principle and aspects of a thing, naturally conforming to the form of a thing. When considered absolutely and without form attributed to it, it is purely potent in existence, and called prime matter. When made “signate,” or when given form, it allows for a species to be individuated from the general form to specific forms (eg humanity in general is expressed in these humans who have such and such varied material attributes).

Essence: what it is to be that which a thing is, or the definition of a thing; when considered absolutely, it is a collection of potencies constituting a form.

Being: to be, act qua act, that which posits something into reality, or the act of existence. An act is only actual insofar as it made so by being.

Substance: an essence which in some degree has being, or the admixture of being and essence. A subsisting thing is a real thing, or an essence which is posited into reality. In most manners of speaking, the substance is that part of the essence of which without being posited in reality the thing in question would not exist. The Form of a thing.

Accident: that which can change regarding a thing, as afforded by its essence, without that thing becoming another thing; the parts of the essence of which without being posited in reality the thing in question may still exist. This is including mental, ontological, and physical states which may be subject to change. The categories of accidents are:

  1. Quantity: the amount of matter a thing has.
  2. Quality: the type of a thing (eg white, black, grammatical).
  3. Relation: how it compares and contrasts to other things.
  4. When: the moment of time in which a thing is.
  5. Location or Position: the place where a thing is.
  6. Posture: the arrangement of a things parts (eg sitting, standing).
  7. Action: the causing of a change in something.
  8. Passion: the reception of a change from something.
  9. State or Habit: the result of a passion (eg burned, clothed), or simply having some physical attribute (eg having arms, hairy).

Nature: the substance insofar as it causes a thing to act or be a certain way; hence, it is said that nature is the derivative of substance, because nature is determined by what a thing is, which is its substantial identity.

Genus: the upper category/class of a thing; all of the species under a genus have the genus’ definitive traits (substantial form) in common.

Species: the lower category/class of a thing; all members of a species have commonalties (shared forms) exceeding the “generic” definition of the genus (substantial form) of which they are under—those commonalities which exceed the genus’s definition define the species.

Quiddity or Quidditas: that which makes a thing a member of a species and/or genus—the aspects (forms) of its essence which it has in common with other things.

Haeccity or Hæccitas: that which distinguishes a thing as an individual from other members of its class—the aspects (forms) of its essence or substance which it does not have in common with other things.

Suppositum: An individual subsisting thing; used to remove the ambiguity of the term “thing,” which may refer to that which does not subsist.

Sufficient Cause: a cause which necessitates an effect; without this, there can be no effect, and if there is no effect, the sufficient cause did not occur.

The Four Causes: Causation can be divided into the following categories:

  1. Efficient: causation which is the source of or allows for change.
  2. Material: causation by the material constituents of a thing.
  3. Formal: causation by the formal constituents of a thing.
  4. Final: causation in respects to the reason; “telos”/”final end” as a cause.

Phantasm: the mental image of or information about a thing as received by the senses; that from which the intellect abstracts universals after having perceived a material thing.

Power: an innate ability of something.

Soul: the substance of a living, naturally material thing, which can be be classified as one of the following types:

  1. Vegetative: natural powers of growth, healing, reproducing, and being nourished.
  2. Sensitive: vegetative powers and the power of perceiving, recalling perceptions, and reacting to perceptions.
  3. Rational: Sensitive powers and the power of cognition, or the ability to understand and use abstractions by way of the phantasms.