What does the word ‘epiphenomena’ mean?

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Increase your vocabulary and you’ll make your writing much more precise. That’s why I provide a word of the week. Today’s word: epiphenomena….

When a word is similar to a better known cousin, sometimes it’s harder rather than easier to discern the meaning  of the lesser known term.

Such is the case with the word epiphenomena, which I spotted in the wonderful book, Why We Sleep by Matthew Walker. Here is how Walker used it:

It was long thought that dreams were simply epiphenomena of the stage of sleep (REM) from which they emerge.

Most of us know that a phenomenon is a fact or situation that is observed to exist or happen — especially one whose cause or explanation is in question. Here’s an example: “Glaciers are unique and interesting natural phenomena.”

If I had a better working knowledge of Greek, I’d have known that the prefix epi– means “upon, at, close upon (in space or time), on the occasion of, in addition, also.”

In any case, it turns out that an epiphenomenon is a secondary effect or byproduct that arises from a process. The word has two distinct senses: one that suggests known causation and one that suggests the absence of causation, or, at least, a reservation of judgment about it.

The example above from Walker, shows a non-causal relationship.

The term is used in metaphysics, philosophy, psychology and medicine. Use of the word epiphenomena dates back to 1706 (although peak usage appeared to occur in 1995.)