In Layman’s Terms, What Is the Meaning of ‘Layman's Terms’?

Whenever someone begins rattling off some esoteric or specialized knowledge, someone may speak up to remind them they’re addressing people who aren’t versed in their expertise, whether they’re a plumber explaining why your sewer line is backing up, or a physician who wants to offer an anatomy lesson.

Often, they’ll be told to explain it in “layman’s terms.” A simplified explanation will follow, and everyone will be happy. (Except the guy with the clogged sewer line and an exorbitant bill.) But what exactly are layman’s terms? Who is this layman who needs everything stripped of nuance and tech-speak? Is it a synonym for dumb?

According to Merriam-Webster, layman was likely first used back in the 15th century. It has roots in French and Late Latin and derives from the Greek word laikos, or “of the people.” The adjective lay meant an entity unrelated to the clergy or of non-ecclesiastical origins; a layman was a non-clerical person unaffiliated with a church.

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Over time, layman took on meaning apart from religious orders and referred to anyone who was outside of a profession or trade. A lawyer might need to explain the vagaries of the court system to a layman—their client. Or, a pilot could attempt to explain how to land a plane to a layman at a social gathering. Layman’s terms are therefore a summary that can be easily understood by anyone.

A physician might, for example, explain a clogged artery with reduced blood flow from plaque build-up by comparing it to a drinking straw [PDF]. As the straw narrows, it becomes harder for liquid—or blood—to pass through it. In layman’s terms, you need a cardiologist.

A call for something to be explained in layman’s terms often follows large news stories, as in the case of coronavirus or a political discussion. A complicated bill might warrant a simplified summary; so might a scientific breakthrough or an injury suffered by a prominent sports figure. It often follows a demand for understanding after a layman feels alienated by jargon.

Referring to non-fungible tokens (NFTs) in 2021, for example, New York Times columnist Kevin Roose explained that “an NFT, in layman’s terms, is a new kind of digital collectible item that is stamped with a unique bit of code that serves as a permanent record of its authenticity and is stored on a blockchain, the distributed ledger system that underlies Bitcoin and other cryptocurrencies.”

While the phrase generally denotes a concession to those outside a realm of expertise, it can sometimes have negative connotations. To wit: this 1897 passage in System of Medicine by T.C. Allbutt:

“The assertion so frequently made by ignorant or unscrupulous laymen that the [medical] profession has been influenced…”

Layperson or laypeople are, perhaps surprisingly, not new synonyms. They also date back to the 15th century.

Curiously, usage of the word layman (in books, at least) appeared to peak in the 1950s before hitting all-time lows in the 2010s. It’s possible the easy availability of information via the internet has made fewer laypeople of us all.