ONTOLOGY TERMINOLOGY
December 11, 2025•2,002 words
📘 ONTOLOGY TERMINOLOGY
📚 1. BEING & EXISTENCE
Being — the condition or status of whatever there is (the realm of entities and their natures).
Example: “Triangularity” as the attribute or nature that makes something a triangle (abstract aspect).
Existence — the property of an entity that it is instantiated in reality (the fact that something is present).
Example: The specific triangle drawn on this page (an existing, instantiated triangle).
Caveat: Some traditions treat "being" as broader than mere existence (includes possible/abstract entities); clarify your usage when necessary.
🧱 2. ENTITY & ARISTOTELIAN FOUR CAUSES
Entity — anything that can be referred to as an object of discourse (physical objects, events, properties, numbers, propositions).
Example: The capacitor on my desk is an entity.
Four Causes (Aristotle):
- Material Cause — the matter out of which X is made.
Example: Ceramic and aluminium for a capacitor's plates. - Formal Cause — the pattern, structure, or essence that makes X the kind of thing it is.
Example: Two conductive plates separated by a dielectric in a capacitor. - Efficient Cause — the process or agent that brings X into being.
Example: The manufacturing steps that assemble the capacitor. - Final Cause — the purpose or function for which X exists.
Example: The capacitor’s role in storing charge to stabilize voltage.
🧍 3. INDIVIDUAL & UNIVERSAL
Individual (Particular) — a single, concrete or instantiated entity.
Example: The capacitor with serial #A123.
Universal — a property or type that can be instantiated by many individuals.
Example: The property being a capacitor or the type “capacitor.”
Note: Universals vs. particulars is an ontological debate (realist vs. nominalist). Here we use the standard realist-friendly wording.
⚙️ 4. ESSENCE & ACCIDENT
Essence — a set of properties an entity must have to be the kind it is (necessary conditions).
Example: Having three straight sides is essential to being a Euclidean triangle.
Accident — a contingent property an entity can gain/lose without ceasing to be the same kind.
Example: A triangle’s colour or size.
🪞 5. IDENTITY & PERSISTENCE
Identity — what it is for an entity to be the very same entity (criteria of sameness).
Example: The identity conditions of a person include continuity of a particular biological organism (one common criterion among many).
Persistence — how an entity continues to exist through time and change (accounts include endurantism and perdurantism).
Example: The “Ship of Theseus” raises the persistence question when planks are replaced.
Caveat: There are multiple theories (endurantism/perdurantism) — state which you adopt in downstream work.
🌱 6. POTENTIALITY & ACTUALITY
Potentiality — a dispositional or capacity-like state that can be realized under suitable conditions.
Example: A seed’s capacity to grow into a tree.
Actuality — the realized or manifest state of what was potential.
Example: The mature tree that grew from the seed.
📐 7. ABSTRACT & CONCRETE
Abstract — entities that are not spatiotemporally located and are not causally efficacious in standard ways (numbers, propositions).
Example: The number 7.
Concrete — spatiotemporally located entities that can causally interact.
Example: This apple on my table.
🔢 8. DISCRETE & CONTINUOUS
Discrete — composed of distinct countable units; elements separated by identity.
Example: Ten chairs in a room.
Continuous — a continuum not naturally divided into countable discrete units (modeled by continua).
Example: The volume of water in a river (modeled as a continuous quantity).
🪨 9. SUBSTANCE — FORM — MATTER
Substance — an entity that underlies properties and has ontological priority in some frameworks (the 'thing itself').
Example: The statue considered as a persisting object.
Form — the organizing principle or structure that makes matter into a particular kind.
Example: The statue’s shape (the arrangement making it a depiction of David).
Matter — the physical stuff composing an object.
Example: The marble from which the statue is carved.
🔔 10. OCCURRENCE
Occurrence — a single, time-bound event or instance of happening (token).
Example: The lightning strike at 14:02 UTC on 11 Dec 2025.
🌈 11. PHENOMENON
Phenomenon — an appearance or event as experienced (often used in epistemology/phenomenology).
Example: The rainbow observed after rain — the perceptual phenomenon.
🔄 12. STATE — EVENT — PROCESS
State — a condition or property of an entity at a time.
Example: Water in the solid state (ice) at 0°C.
Event — an occurrence that effects change between states.
Example: Melting begins at time t₀.
Process — a sequence of events or state-changes extended through time.
Example: The entire water cycle: evaporation → condensation → precipitation.
🎛️ 13. DISPOSITION & CAPABILITY
Disposition — an intrinsic tendency or propensity under circumstances (often modal).
Example: Glass’s disposition to shatter when struck.
Capability (Ability) — the power to perform an action (can be realized via skills, mechanisms).
Example: A human’s capability to speak (language competence).
🧭 14. MODALITY
Modality — modes of truth or being: possibility, actuality, necessity.
- Possible: true in at least one possible world.
- Actual: true in the actual world.
- Necessary: true in all possible worlds.
Example: “2+2=4” is necessary; “It may rain tomorrow” is possible.
📊 15. QUANTITY & QUALITY
Quantity — measure or count of how much / how many (numerical magnitude).
Example: 5 kilograms.
Quality — attributes describing kinds or features (non-numeric properties).
Example: The apple’s redness.
🗺️ 16. SPACE — TIME — FORCE
Space — the dimension or region in which objects are located (geometric/spatial relations).
Example: The coordinates of a room.
Time — the ordering dimension of events (temporal sequence).
Example: 11:00 AM on 2025-12-11.
Force — (in physics) an interaction that causes acceleration or state-change.
Example: The push that accelerates a block.
📈 17. FUNCTION & PERMUTATION
Function — a mapping from inputs to outputs (mathematical/semantic mapping).
Example: f(x) = x² maps 2 → 4.
Permutation — a bijective rearrangement of elements of a set.
Example: Reordering (A,B,C) → (C,A,B).
🔐 18. CONDITION & CONSTRAINT
Condition — one or more requirements that must obtain for a fact/event to occur (enabling).
Example: Presence of oxygen as a condition for combustion.
Constraint — limitation that restricts the possible states or evolutions.
Example: Fuel capacity limits fire duration.
🧩 19. MEREOLOGY — PARTS, WHOLES & RELATED NOTIONS
Part — an entity that is included within another (the whole).
Example: Wheel is a part of a car.
Whole — entity composed of parts in a certain structure.
Example: The car.
Proper Part — part distinct from the whole (not identical).
Example: Engine is a proper part of the car.
Overlap — two entities share at least one common part.
Example: Two adjacent plots share a border segment.
Fusion / Sum — the object that is the mereological sum of given parts.
Example: The collection of all bricks forming a wall considered as one object.
Caveat: Mereological theories vary (classical mereology vs. non-standard approaches). State which mereology you adopt if precision matters.
🧲 20. ONTOLOGICAL DEPENDENCE & RELATED NOTIONS
Existential Dependence — A depends on B for its existence (A cannot exist unless B does).
Example: A hole depends existentially on the object (a hole cannot exist without its host).
Constitution — relation where one entity (constituted) is made of another without identity (statue constituted by lump of clay).
Example: The statue is constituted by the lump, though some argue they are identical—philosophers disagree.
Supervenience — higher-level properties are fixed by lower-level properties (no change at higher-level without change at lower-level).
Example: Mental properties supervene on neural properties (standard formulation in philosophy of mind).
🕰️ 21. IDENTITY THEORIES (ADVANCED)
Endurantism (3Dism) — objects are wholly present at each moment of their existence.
Example: A chair exists wholly at t₁ and t₂.
Perdurantism (4Dism) — objects persist by having temporal parts (time-slices).
Example: "You-at-age-5" is a temporal part of you.
Counterpart Theory — across possible worlds identity is represented by counterparts rather than strict identity.
Example: Your counterpart in another possible world is not you but a similar individual.
🌍 22. POSSIBLE WORLDS & MODAL ONTOLOGY
Possible World — a complete way the world might have been (a maximal state).
Example: A possible world where Rome never fell.
Actual World — the world we inhabit (the world considered actual).
Example: Our world.
Necessity / Contingency / Possibility — standard modal categories (see Modality above).
Impossible Worlds — sometimes posited for handling contradictions or intensional contexts (non-standard).
Example: A "world" where square circles exist (use with caution; non-classical frameworks).
📦 23. CATEGORY THEORY / ABSTRACT STRUCTURE (FOUNDATIONS)
Object (categorical) — an abstract node in a category.
Example: A set A in category SET.
Morphism — arrow from one object to another preserving structure.
Example: f: A → B.
Functor — map between categories preserving structure.
Example: A functor sending each graph to its adjacency matrix.
Natural Transformation — a morphism between functors that is 'natural' in its components.
Example: A canonical reindexing map between two functorial constructions.
🧬 24. FORMAL ONTOLOGY (BFO / DOLCE) — SELECT NOTIONS
Continuant — an entity that endures through time while retaining identity (3D-ish notion used in BFO).
Example: A human organism.
Occurrent — an event or process that unfolds in time.
Example: A concert.
Dependent Continuant — a property that cannot exist without a bearer.
Example: The colour of a leaf depends on the leaf.
Quality Region — domain of a quality (e.g., temperature scale).
Example: Temperature values 0–100°C.
Process Boundary — an instantaneous boundary marking process change (modeling device).
Example: The exact instant water crosses boiling point in an experiment.
🖥️ 25. AI & COMPUTATIONAL ONTOLOGY (APPLIED NOTIONS)
Class (Type) — set of individuals sharing core properties.
Example: Class Vehicle.
Instance (Individual) — concrete member of a class.
Example: Car VIN 1HGBH41JXMN109186.
Object Property (Relation) — relation between individuals.
Example: partOf(wheel, car).
Data Property — relation between an individual and a data value.
Example: car.maxSpeed = 180 (km/h).
Reasoner — software component that derives implicit facts from explicit axioms (ontology inference).
Example: An OWL reasoner deriving that all humans are mammals given axioms.
⚛️ 26. METAPHYSICAL STRUCTURE & ONTOLOGICAL LEVELS
Fundamental Level — the ontology layer considered metaphysically basic (varies by theory).
Example: In physics, fundamental fields or particles.
Emergence — phenomena at higher levels arising from but not reducible to lower-level organization.
Example: Wetness emerges from H₂O molecular interactions.
Grounding — metaphysical dependence: facts obtaining in virtue of more fundamental facts.
Example: The fact "the apple is red" grounded in surface reflectance microstructure.
Natural Kinds / Artifact Kinds — distinction between naturally occurring categories and human-made kinds.
Example: Electron (natural kind) vs. Smartphone (artifact).
🔬 27. SCIENTIFIC ONTOLOGY (MODELS)
Field Ontology — modeling reality as continuous fields (physics).
Example: Electromagnetic field.
System Ontology — entities defined by interacting components (systems theory).
Example: The cardiovascular system.
Computational Ontology — describing phenomena as information structures.
Example: Gene sequences represented as digital data.
📜 28. META-ONTOLOGY
Quinean Criterion — ontological commitments arise from quantification in best theory ("To be is to be the value of a bound variable").
Example: If your science quantifies over electrons, you are committed to electrons.
Neo-Aristotelian / Grounding Approaches — focus on explanation in terms of substances and grounds.
Example: Explaining biological function in terms of organismal roles.
Ontological Commitment — what entities a theory posits as existing.
Example: Committing to spacetime points vs. fields in physics.
🧴 29. ADVANCED SEMANTIC TERMS
Trope — a particular instance of a property (particularized property).
Example: The particular redness of this apple (not the universal 'redness').
Event Token vs. Event Type — token = particular occurrence; type = general kind.
Example: Token: the 2005 explosion in Lab A; Type: 'explosion'.
Intension vs. Extension — intension = concept/meaning; extension = set of instances.
Example: Intension of 'prime number' vs. its extension {2,3,5,7,...}.