• theory •
Pronunciation: thee-ê-ree • Hear it!
Part of Speech: Noun
Meaning: 1. A scientifically tested and proven explanation; a hypothesis that has been tested and confirmed. 2. An idea, notion, supposition. 3. The structure or conception of something, as the theory of music.
Notes: The second meaning of this word demonstrates how it has been confused so long with hypothesis that many speakers do not understand the difference between the two. In science, theories and hypotheses are explanations of phenomena. However, a theory has been scientifically proven, while a hypothesis has not. The adjective for theory is theoretical and someone who creates theories is a theoretician who theorizes.
In Play: It is important to keep theory and hypothesis discrete when discussing scientific matters: "When Miss Dakin says evolution is only a theory, it is because she thinks it is a hypothesis that hasn't been proven." Outside science, of course, we use the word figuratively referring to unsubstantiated beliefs: "Melanie's theory that dogs prefer fresh green vegetables to meat was laid to rest when her animal ran away from home."
Word History: Today's Good Word is an English reworking of Latin theoria, a word Latin borrowed from Greek theoria "looking at, considering". The Greek noun came from the verb theorein "to look at, to consider" from theoros "spectator". Theoros is made up of the remains of thea "a view" + the root of horan "to see". Thea, of course, is also visible in another English borrowing from Greek via Latin: theatre, a place where spectators view plays and concerts. The Greek word was theatron from thea + -tron "place of".