Principal (school), head of a primary or secondary school

Principal, in business, a person who is the owner of a business case and as such the person who delegates and controls the execution of the investment projects

The principal sum is the original amount of a debt or investment on which interest is calculated

A security principal is an entity that can be positively identified and verified via a technique known as Authentication.

Organ stop on a pipe organ

Principal (commercial law), a person who authorises an agent to act to create a legal relationship with a third party

Provost (education), chief academic officer of a university

Chancellor (education), the head of a university

Principal Financial Group is a life insurance company traded on the NYSE.

Dean (education), a person with significant authority

A principal ideal in ring theory in mathematics is an ideal with a single generator

Principal, Cape Verde is a village.

Principal (university), chief executive of a university

Principal (criminal law), one (or more) primary actor(s) in a criminal offense for which other actors may be criminally liable as accomplices, accessories or conspirators.

A musician in an orchestra who either plays the first part (wind instruments), or who sits in the first chair and leads a section (of string instruments) in playing the same part.

A performer in an opera or musical who takes a more or less prominent part in the action, and sings solo or in small ensembles. Contrasts with chorus.

Principal or Principal Officer is a senior management grade (now grade 7) in the British Civil Service and the Irish Civil Service.