Definitions of Theory

1: the analysis of a set of facts in their relation to one another

2: abstract thought : speculation

3: the general or abstract principles of a body of fact, a science, or an art <music theory>

4a : a belief, policy, or procedure proposed or followed as the basis of action <her method is based on the theory that all children want to learn> b : an ideal or hypothetical set of facts, principles, or circumstances —often used in the phrase in theory <in theory, we have always advocated freedom for all>

5: a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena <the wave theory of light>

6a : a hypothesis assumed for the sake of argument or investigation b : an unproved assumption : conjecture c : a body of theorems presenting a concise systematic view of a subject <theory of equations>