Principal vs Principle
Quick answer: Principal is a person in charge or the main thing (also your loan's principal). Principle is a rule, law, or belief. The school leader is your principal; honesty is a principle.
Principal
Noun/adjective: the head of a school; first in importance; the original sum of a loan.
“The principal spoke at the assembly.”
Principle
Noun: a fundamental rule, truth, or belief.
“She refused on principle.”
How to remember it
The princiPAL is your PAL; a princiPLE is a ruLE.
Common mistake
'A matter of principal' — beliefs and rules end in -ple.