Categorical is a synonym of absolute and definite that describes something that is said in a very strong and clear way. It can also mean "of, relating to, or constituting a category" or "involving, according with, or considered with respect to specific categories."

// The organization has issued a categorical denial about its involvement in the deal.

// The library relies on a categorical system for classifying books.

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"In the last 15 years or so, psychiatry has embraced what's called a dimensional approach, based on the idea of scales and spectrums of trait and symptom severity. That replaced the categorical approach, which took a more binary view of mental syndromes and assessed whether conditions were present or not." — David Adam, Smithsonian Magazine, 3 Aug. 2023

The ancestor of categorical and category has been important in logic and philosophy since the days of Aristotle. Both English words come from the Greek word katēgoria, which Aristotle used to name the ten fundamental classes (also called "predications" or "assertions") of terms, things, or ideas into which he felt human knowledge could be organized. Ironically, although those categories and things categorical are supposed to be absolute and fundamental, philosophers have long argued about the number and type of categories that exist and the role they play in our understanding of the world. High-level philosophical disputes aside, the word categorical continues to sometimes describe an absolute assertion, one that involves no conditions or hypotheses—for example, the statement "hot dogs are sandwiches all humans are mortal."