The word "cardinal" is an adjective that means something that is of primary importance or fundamental. It can refer to essential principles, major rules, or the main aspects of something. In a different context, "cardinal" can also be a noun that refers to a high-ranking official in the Catholic Church or a type of bird known for its bright red color, particularly in the species Cardinalis.
The term "cardinal" comes from the Latin word "cardinalis," which means "pertaining to a hinge." This etymology reflects the idea of something being essential or pivotal, much like a hinge is essential for a door to function properly.