What are “layman’s terms”?

Historically, lay meant ‘not ecclesiastical’ - specifically, not a member of the Priesthood of the Christian Church. A layman would be anyone who has not taken holy orders. Priests, historically, were far better educated than everyone else; in the middle ages even the lowliest novice monk could read and write better than a king. This meant that clergy (another word for people who have taken vows of holiness) had a much larger, and often more interesting vocabulary than everyone else. It also meant that they developed a jargon - an internal or technical vocabulary used only among them.

A layman, having less education and a smaller vocabulary, might overhear a couple of clergymen discussing something that he was quite unable to understand - or only partly able to understand.

Today, everyone is better educated, and technical terms abound. Almost any field of activity has it’s own jargon, which has even led to the same word having completely different meanings to different people in different situations. To a mathematician, differentiation is the opposite of integration in calculus. To a biologist, differentiation refers to the characteristics that define species. To a sociologist, integration refers to the process of cultural mixing and adaptation while to a manager, it just refers to how well someone fits into a team.

In layman’s terms means using language that is not jargon, that is not specific to a particular domain or area of activity. So when your manager tells you that the organization is having ongoing issues with horizontal integration, you can express this in layman’s terms as ‘different departments are still not communicating well.’

In layman’s terms, layman’s terms are language that (in theory) anyone can understand.

Layman’s terms mean using language that can be understood by the ordinary person, who is not an expert in jargon or specialist vocabulary etc.

A synonym would be to say “in plain English”.

The derivation of the use of the word layman (and hence layman’s terms ) comes from the church.

A lay person (or a member of the laity ) is someone who is not a clergyman, so a layman’s term is a simpler (less esoteric) piece of language that would he more accessible to someone who has not studied theology.

These days we use the term layman for any non-specialist, not just for matters involving the church, (such as lay preachers).

There are sometimes lay members on tribunal panels for example. Hence we might use layman’s terms for matters where the public deal with any specialist profession, such as doctors, lawyers or technologists.

Because laymen (or laywomen, laypersons, laypeople) are common, everyday people. The “lay” part comes from the Greek laikos , meaning “ordinary people”, according to Wikipedia. It made its way to English, becoming “lay”.

Laypersons are, according to the dictionary definition, people who are not skilled or professionals in a particular field. That pretty just means us muggles

A layman’s term is a way of explaining an idea or thing without using jargon specific to the field to which it belongs. It is an explanation through which an average person who has made no in depth study of the topic (layman) will understand the basic concept being described.

As Arad Namin wrote, a layman’s term does not convey the full complexity of the concept being discussed, but gives sufficient data for the layman’s purpose or information.

It is also worth noting that layman’s terms undergo change over time.

Terms that are initially considered esoteric gradually make their way into mainstream language, via popular media while others fade out. Today, every child would be familiar with words like e-mail, website, etc. They can now be used to explain something in layman’s terms. But there was a time when these words would have needed explanation themselves.

On the other hand, some terms no longer stay relevant and go out of mainstream use. Most people would need an explanation for words like hussif, alternately spelled housewife today. (It means a sewing kit.) This word can no longer be used to explain some other idea in layman’s terms.

A layman is a person without any specialized knowledge in any subject.

When any concept from any branch of study(science, economics, mathematics) that requires higher level of understanding than that of any average person. When this concept is simplified and explained in terms of a layman is said to be a concept in ‘Layman’s Terms’ .

For example, Let’s try to understand general theory of relativity in layman’s terms,

We think of gravity as a invisible force attracting two bodies according to Newtonian mechanics. But according to Einstein gravity is not an invisible force but an effect of mass on space-time curvature causing a warping of objects around it.

This is general relativity in layman’s terms, it can be understood by any person given she/he is literate in English and has a little knowledge about science from school, coaching etc.