principal and principle

Principal means main.
A principal is the head (of a department).
Principle means general law or code of conduct.

Writers occasionally confuse the words principal and principle.


In its most common role, principal is an adjective meaning main or key.

Examples: The word principal can also be noun mean head or chief. It is commonly used to denote head teacher in the US.


The word principle is a noun. It has a range of meanings, including rule, belief, tenet and theory.  In general, principle offers the idea of general law or code of conduct.

A Quick Test


If you imagine that the l on the end of principal looks like a 1, then the last two letters become A1.  This may help you to remember that principal denotes the most important or main.

When referring to a loan, the principal (or principal sum) is the original amount of a debt or investment on which interest is calculated.

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See Also

What are nouns? What are verbs? List of easily confused words