A layperson is someone without specialized training or professional expertise in a particular field. When doctors explain a medical condition in terms a layperson can understand, they're using simple language instead of technical jargon that only other doctors would know. When a scientist describes quantum physics to a layperson, she avoids complex equations and uses everyday examples instead.

A brilliant mathematician might be a layperson when it comes to car engines. A professional chef is a layperson when it comes to computer programming. Being a layperson means you haven't spent years studying that specific subject, though you may be highly knowledgeable in other areas.

You'll often see the phrase “in layperson terms,” which means explaining something without specialized vocabulary. If your dentist says “you have a cavity in your first molar,” she might add, in layperson terms, “that's a hole in one of your back teeth.” The goal is making complex information accessible to everyone, not just experts.