To make plain, manifest, or intelligible; to clear of obscurity; to illustrate the meaning of.
"The teacher used a diagram to explain the complex concept so that every student could finally understand it clearly."
In plain English: To explain means to make something clear by describing how it works or why it happened.
"Please explain how to fix this leaky faucet."
Usage: Use explain when you want to make something difficult to understand simple and clear by giving details or reasons. Avoid using it merely to state a fact, as its core purpose is to illuminate meaning rather than just report it.
The word "explain" comes from the Latin verb explanō, which literally meant to flatten or spread something out so it becomes clear. It entered Middle English through Old French and eventually replaced the earlier Old English term reċċan.