Definition
Etymology is the study of word origins — how a word entered a language, how its form and meaning changed over time, and what earlier words it descends from. Done properly, it relies on documentary evidence: dated texts that show a word in use, and established patterns of sound change across related languages.
It is also one of the most fertile grounds for misconception. The Book of Common Fallacies returns repeatedly to false etymologies — tidy, memorable origin stories for words and phrases that are simply invented. These so-called folk etymologies are popular precisely because they are more satisfying than the messy documentary truth.
Why it matters
How it works
A false etymology spreads the same way any myth does. Someone offers a clever account — a word is supposedly an acronym, or comes from a vivid historical incident — and the story is memorable enough to be retold without ever being checked. The neatness that makes it appealing is itself the tell, because genuine word histories rarely resolve into a single tidy moment.
Real etymology resists this by demanding evidence: the earliest recorded uses, the documented spellings, the regular sound correspondences between languages. A claimed origin that cannot be supported by such records is treated as folk etymology, however widely it is repeated.