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principal vs principle

Principal means main or most important — and, as a noun, the head of a school or the original sum of a loan. A principle is a fundamental rule, standard or belief. Only principle is ever an idea you hold.

The difference

• principal (adjective) — main, chief, most important
• principal (noun) — a head person, or the original amount of a loan
• principle (noun) — a rule, standard or fundamental truth

Examples

• The principal reason for the change was cost.
• She refused on principle.

How to remember

Your pal is your princiPAL; a rule is a princiPLE (both end in -le, like rule).

The common trap

Writing 'a matter of principal' — a belief is always principle.

These distinctions are exactly what Word Meaning and Contextual Word Choice questions test. Read the Word Meaning guide or Contextual Word Choice guide, then practise the drill.