theory

Meanings

1. 1
   noun

   A set of ideas that explains how or why something happens, supported by evidence.

   Darwin's theory of evolution changed how we understand life.

2. 2
   noun

   An idea or guess that has not yet been proven.

   My theory is that he missed the train.

3. 3
   noun

   The general principles or rules of a subject, as opposed to its practice.

   She knows music theory but rarely plays in public.

4. 4
   noun

   A field of study that tries to fully describe a class of things.

   Knot theory studies how curves can be tied in space.

From Middle French théorie, from Late Latin theōria, from Ancient Greek θεωρία (theōría, “contemplation, divine perspective, speculation, a looking at, a seeking”), from θεωρέω (theōréō, “to look at, view, see, consider, examine”), from θεωρός (theōrós, “spectator”), from θέα (théa, “view, perspective, sight”) + ὁράω (horáō, “to see, look”) [i. e. θέαν ὁράω (théan horáō, “see, look at a view; survey + genitive”)].

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