- Something or someone that holds the highest rank or is the most significant among other related things or individuals
- A person or thing that holds a prominent or high-ranking position
- A person or entity who takes part in an action or transaction, often holding a certain level of control or authority
- An individual who engages others to carry out tasks for them under their general supervision or direction
- An individual who directly commits a crime or encourages or assists another individual to commit a crime
- The person who is primarily responsible for fulfilling a legal obligation, or one who will ultimately carry the responsibility because of a duty to cover someone else's losses
- An original amount of money that produces interest, is owed as a debt, or is used as a financial resource
- The loan company sent a notice to the debtor that the principal of the loan was due.
- The bank increased its profits by investing the principal in various business ventures.
- The police have captured one of the two criminals who acted as the principal in the bank robbery.