What does categorise mean?
To categorise is to sort things into groups according to shared qualities — a fundamental act of organisation that underlies science, libraries, databases, and everyday tidying alike. A biologist might categorise species by genus, an accountant might categorise expenses by type, and a streaming service might categorise films by genre. The word functions as a transitive verb: you categorise something, whether objects, people, ideas, or information. Its tone is neutral to formal, appearing frequently in academic writing, business reports, and technical documentation rather than casual chat. Notably, saying that something "defies categorisation" is itself a meaningful use — it signals that the thing is too unusual, hybrid, or complex to fit neatly into any established group. "Categorise" is the standard British spelling, while "categorize" predominates in American English; both derive from the Greek "kategoria," meaning accusation or predication, which itself traces back to speech in the public assembly. Understanding this word means understanding how humans impose order on a complicated world.
verbTo arrange or classify things into categories according to their shared characteristics; to place within a system of classes or groups.
- To sort people, objects, ideas, or information into distinct classes or groups based on shared characteristics.
"The librarian spent the afternoon sorting and categorising the donated books by subject."
"Researchers categorised the responses into three broad themes."
"His music resists easy categorisation — it blends jazz, folk, and electronic elements."
Every time you categorise something, you're using a word rooted in the ancient Greek agora — because to categorise originally meant to speak in the public assembly.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of categorise
The word derives from the Greek "kategoria," meaning "accusation" or "predication," formed from "kata-" (down, against) and "agoreuein" (to speak in the assembly), which comes from "agora," the public marketplace and gathering place of Greek city-states. The philosopher Aristotle used "kategoria" in a technical sense for his fundamental classes of being, giving the root lasting philosophical weight. English adopted "category" via Latin "categoria," and "categorise" emerged later as the verb form, gaining wide currency in the eighteenth and nineteenth centuries alongside the growth of scientific classification systems.
Related word forms
How categorise is actually used
"Categorise" with an s follows British spelling conventions; American English uses "categorize." The verb carries a neutral, often academic or administrative register, and it can be used both transitively ("categorise the files") and passively ("the specimens were categorised"). In figurative use, saying something "defies categorisation" implies it is unusually original or hard to pin down.
Easily confused with categorise
"Categorise" is simply the British spelling of the same verb, while "categorize" with a z is the standard American spelling; they mean exactly the same thing.