Principle vs Principal

Updated on 5/2/2013. Many thanks to Mike Ditto for pointing out that I had made a mistake in the original article and used the principle definition twice. I have updated the article with a better definition for principal.

I constantly see principle and principal used interchangeably. I see job posting for Principle Engineer positions as well as articles about Scheduling Principals in Java Applications (see It is understandable that these words can be confused since they look and sound alike. They have very different meanings though.

When used as a noun, principal (according to refers to "a person who takes a leading part in any activity, as a play; chief actor or doer." As an adjective, it is "highest in rank or authority." This is the correct word to use when referring to Principal Engineer title or positions.

A principle is "a rule of action or conduct" (see It would have been the correct word to use in the title of the article referred to above.

The reality is that I will refuse to apply for a Principle Engineer position and I am very unlikely to read an article that misuses the word principals in a title. Call it a question of principles if you must.