Noun

(varieties)

The quality of being varied; diversity.

A specific variation of something.

A number of different things.

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, title=(The Celebrity), chapter=4 , passage=One morning I had been driven to the precarious refuge afforded by the steps of the inn, after rejecting offers from the Celebrity to join him in a variety of amusements. But even here I was not free from interruption, for he was seated on a horse-block below me, playing with a fox terrier.}}

* {{quote-magazine, date=2013-01, author=Katie L. Burke, volume=101, issue=1, page=64, magazine=(American Scientist)

, title= Ecological Dependency , passage=In his first book since the 2008 essay collection Natural Acts: A Sidelong View of Science and Nature , David Quammen looks at the natural world from yet another angle: the search for the next human pandemic, what epidemiologists call “the next big one.” His quest leads him around the world to study a variety of suspect zoonoses—animal-hosted pathogens that infect humans.}}

A state of constant change.

(taxonomy) A rank in a taxonomic classification, below species and subspecies.

(cybernetics) The total number of distinct states of a system.

(cybernetics) Logarithm of the base 2 of the total number of distinct states of a system.

(linguistics) A term used for a specific form of a language, neutral to whether that form is a dialect, accent, register, etc. and to its prestige level.

The class of all algebraic structures of a given signature satisfying a given set of identities.

Noun

(categories)

A group, often named or numbered, to which items are assigned based on similarity or defined criteria.

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The traditional way of describing the similarities and differences between constituents is to say that they belong to categories'' of various types. Thus, words like ''boy'', ''girl'', ''man'', ''woman'', etc. are traditionally said to belong to the category''' of Nouns, whereas words like ''a'', ''the'', ''this'', and ''that'' are traditionally said to belong to the ' category of Determiners.

This steep and dangerous climb belongs to the most difficult category .

I wouldn't put this book in the same category as the author's first novel.

(mathematics) A collection of objects, together with a transitively closed collection of composable arrows between them, such that every object has an identity arrow, and such that arrow composition is associative.

One well-known category has sets as objects and functions as arrows.

Just as a monoid consists of an underlying set with a binary operation "on top of it" which is closed, associative and with an identity, a category consists of an underlying digraph with an arrow composition operation "on top of it" which is transitively closed, associative, and with an identity at each object. In fact, a category's composition operation, when restricted to a single one of its objects, turns that object's set of arrows (which would all be loops) into a monoid.