This week’s theme
Words from science that have different senses in everyday use

This week’s words
optics
epicenter
quantum
theory
entropy

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A.Word.A.Day

PRONUNCIATION:

(THEE-uh-ree, THEER-ee)

MEANING:

noun:
1. A set of propositions used to explain some aspect of the natural world, one that has been repeatedly tested and confirmed and widely accepted. For example, Einstein’s theory of relativity or Darwin’s Theory of Evolution.
2. The body of principles belonging to a field. For example, music theory.
3. A speculation.

ETYMOLOGY:

From Latin theoria, from Greek theoria (contemplation), from theoros (spectator), from theorein (to consider, look at), which also gave us theorem and theater. Earliest documented use: 1597.

NOTES:

In science, a theory is a well-substantiated explanation for some aspect of the natural world. In everyday use, a theory is a conjecture. Some people use "just a theory" to discount the theory of evolution, but don't confuse the scientific use of the word with its everyday use. If evolution is just a theory then relativity is also just a theory.

USAGE:

“The theory of evolution explained that every species on earth is related in some way to every other species; more important, we each carry a record of that history in our body.”
Michael Specter; A Life of Its Own; The New Yorker; Sep 28, 2009.

“That is a theory that may soon come to be tested.”
China’s Property Market; The Economist (London, UK); May 31, 2014.

See more usage examples of theory in Vocabulary.com’s dictionary.

A THOUGHT FOR TODAY: