(originally law) Used other than figuratively or idiomatically: see conspiracy, theory. A hypothesis alleging that the members of a coordinated group are, and/or were, secretly working together to commit illegal or wrongful actions including attempting to hide the existence of the group and its activities.

(mathematics) A mathematical theory that models a cluster structure in a random graph to describe the spread of phenomena passing through the edges.

(mathematics, economics, dated) game theory.

(mathematics, economics) A branch of applied mathematics that studies strategic situations in which individuals or organisations choose various actions in an attempt to maximize their returns.

(physics) A generalized theory of eleven-dimensional supergravity that attempts to unify the five superstring theories

An overall explanation of phenomena in a particular discipline or realm of experience such as economics, sociology, or history.

(physics) The theory that all gross matter is composed of atoms. / (physics) Any of several theories that explain the structure of the atom, and of subatomic particles.

(physics) The theories of special relativity and general relativity, two theories in physics developed mainly by Albert Einstein at the beginning of the 20th century from which several important results such as the equivalence of matter and energy and the Einstein field equations are derived.

(dated) atomic theory

The branch of mathematics dealing with the algebraic structure of fields. / (psychology) A theory which examines patterns of interaction between individuals and their environment.