Definition of impenetrable

The word "impenetrable" originates from the Latin verb "penetrare," which means "to enter" or "to pierce." The term was formed by adding the prefix "in-," which signifies negation or reversal, to the root word. In simpler terms, "impenetrable" means "not able to be entered" or "not capable of being pierced." The first recorded usage of the word appears in the 15th century, in the Middle English language. This term has since been adopted into many modern-day languages worldwide, including French, Spanish, and German. Its meaning has remained consistent throughout its history, though its usage has evolved to describe a wide range of things that are difficult to penetrate or understand, such as dense forests, thick fog, or complex theories.