[the.o.ry] n, pl -ries [LL theoria, fr. Gk theoria, fr. theorein] (1592) 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 ~"
4. a: a belief, policy, or procedure proposed or followed as the basis of action "her method is based on the ~ 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 ~, we have always advocated freedom for all"
5: a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena "wave ~ of light"
6. a: 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 "~ of equations" syn see hypothesis