READ THESE ARTICLES
"Principal" Or "Principle"?
The words principle and principal are pronounced in the same way but they do not have the same meaning. Principle is normally used as a noun meaning ‘a fundamental basis of a system of thought or belief’, as in:
This is one of the basic principles of democracy.
Principal, on the other hand, is normally an adjective meaning ‘main or most important’, as in:
one of the country’s principal cities
Principal can also be a noun, where it is used to refer to the most senior or most important person in an organization or other group, such as ‘the deputy principal’. It may also refer to a sum of money lent or invested, on which interest is paid, such as in 'the principal on the loan'.
See more from Usage
Are You Learning English? Here Are Our Top English Tips