theory

Meanings

1. A description of an event or system that is considered to be accurate.
2. A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc.
3. The underlying principles or methods of a given technical skill, art etc., as opposed to its practice.
4. A field of study attempting to exhaustively describe a particular class of constructs.
5. A set of axioms together with all statements derivable from them; or, a set of statements which are deductively closed. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems). The statements may be required to all be bound (i.e., to have no free variables).
6. The standardization and study of fixed sequences of moves, especially in the opening phase of a game.
7. Mental conception; reflection, consideration.
8. A hypothesis or conjecture.

Etymology

Etymology tree Proto-Hellenic *tʰáwā Ancient Greek θέᾱ (théā) Proto-Indo-European *wer-der. Proto-Indo-European *h₃ekʷ-der. Proto-Indo-European *weyd-der. Ancient Greek ὁράω (horáō) Ancient Greek *θεᾱ-(ϝ)ορός, *θεη-(ϝ)ορός (*theā-(w)orós, *theē-(w)orós) Ancient Greek θεωρός (theōrós) Proto-Indo-European *-h₂ Proto-Indo-European *-éh₂ Proto-Indo-European *-i-eh₂ Proto-Hellenic *-íā Ancient Greek -ῐ́ᾱ (-ĭ́ā) Ancient Greek θεωρία (theōría)bor. Late Latin theōrialbor. Middle French théoriebor. English theory Borrowed from Middle French théorie, a learned borrowing from Late Latin theōria, borrowed from Ancient Greek θεωρία (theōría), from θεωρός (theōrós) + -ῐ́ᾱ (-ĭ́ā).