When I looked up the Latin phrase I realized probably if I had to look it up, plenty of other people would too, so I copied the first couple of lines from Wikipedia here to save people the effort.

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Argument from authority (also known as appeal to authority or argumentum ad verecundiam) is a special type of inductive argument which often takes the form of a statistical syllogism.

Although certain classes of argument from authority do on occasion constitute strong inductive arguments, arguments from authority are commonly used in a fallacious manner.

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Since I'm not logically proving anything, I'll refer to an authority, Strunk and White, who say:

"Avoid foreign languages: the writer will occasionally find it convenient or necessary to borrow from other languages. Some writers, however, from sheer exuberance or desire to show off, sprinkle their work liberally with foreign expressions, with no regard for the reader's comfort. It is a bad habit. Write in English"