 Principle vs. Principle Since the usage of these two words is often unclear, we decided to take a closer look. The word principle is used both as a noun and an adjective. When used as a noun, it refers to a person of high authority. For example, Mr. Brown is the principle of this high school. When used as an adjective, principle has the sense of leading or primary. For example, the principle cause of the Great Plague was bacteria transmitted through the bite of an infected rat flea. Principle, on the other hand, is only used as a noun and describes a moral or standard. An example sentence would be, the principle of free speech does not exist in many countries around the world. You can easily remember the difference of the two words by looking at the last three letters of each word. A principle ending in P-A-L can be seen as your pal, but a principle ending in P-L-E or a standard cannot be your pal. That's it for today. See you next time.