Why does the word trivial have the form root word tri meaning three in it?

Answer 1

"Trivial" comes from the Latin word "trivium" which means "an introductory curriculum at a medieval university involving the study of grammar, rhetoric, and logic," literally, a place where three roads meet, from tri (three) and via (road).

This was considered less important than the Quadrivium, the mathematical arts of arithmetic, geometry, astronomy and music. Hence, trivial.

Answer 2

The word "trivial" has the root word "tri-" meaning "three" because in ancient times, concepts were often categorized into three groups: the important, the less important, and the trivial. "Trivial" was used to refer to things that were considered less important or of little significance, hence the connection to the root meaning "three."