Principal or Principle ?
Your choice!
Principal
Exemple : ‘’My principal reason for moving was to be closer to my family.’’
The words "principal" and "principle" are often mixed up. "Principal" is an adjective used before nouns in order to denote that something is the most important. It can also be used as a noun in order to denote a person who is in charge, most commonly of a school.
Principle
Exemple : ‘’The company works on the principle that everyone is equal.’’
"Principle" is a noun used as a synonym of the word "idea."