Emily Dickinson Lexicon

THE'O-RY, n. [Fr. theorie; It. teoria; L. theoria; Gr. θεωρια, from θεωρεω, to see or contemplate.]

1. Speculation; a doctrine or scheme of things, which terminates in speculation or contemplation, without a view to practice. It is here taken in an unfavorable sense, as implying something visionary.
2. An exposition of the general principles of any science; as, the theory of music.
3. The science distinguished from the art; as, the theory and practice of medicine.
4. The philosophical explanation of phenomena, either physical or moral; as, Lavoisier's theory of combustion; Smith's theory of moral sentiments. Theory is distinguished from hypothesis thus; a theory is founded on inferences drawn from principles which have been established on independent evidence; a hypothesis is a proposition assumed to account for certain phenomena, and has no other evidence of its truth, than that it affords a satisfactory explanation of those phenomena. D. Olmsted.