Principle vs. principal
Principle vs. principal: it’s very easy to confuse these two words. Although they sound the same when they’re spoken, their meanings are quite different. Here are two sentences in which the wrong choice has been made:
X The principle aim of the initiative is to make art accessible to everyone.
X There are too many designers who do not understand the basic principals of design.
How to use ‘principle’
Principle is a noun. Its main meaning is ‘a fundamental idea or general rule that is used as a basis for a particular theory or system of belief’. Here are some examples from the Oxford English Corpus that illustrate this sense of principle:
It is a basic principle of criminal law that the accused is innocent until proven guilty.
The school offers students traditional training in the fundamental principles of drawing, painting, and sculpting.
This idea has been the guiding principle behind Canadian and American farm policy at the international level.
They plan to argue that the 1995 statute violates the principles of the Constitution.
In his first book, Ptolemy sets out the general principles of astrology.
A principle is also ‘a rule or belief about what is right and wrong that governs the way in which someone behaves’. In this sense, the word is typically used in the plural form:
He was a tireless crusader for various causes and refused to compromise his principles for the sake of expediency.
I don’t intend to ban anyone from this site because it’s against my principles.
Like her father she had strong moral principles and a dislike for injustice.
Stick to your principles, I told him. Your friends will always stand by you.
He refused, on principle, to pay the fine.
Principle can also be used as an uncountable noun to mean ‘morally correct behaviour’:
Ken is a man of principle who fights for what he thinks is right.
How to use ‘principal’
Principal is most commonly found as an adjective meaning ‘main or most important’. Here are some sentences from the Oxford English Corpus showing the correct use of the adjective principal:
German, US, and English visitors all cited Scotland’s stunning scenery as their principal reason for holidaying in the country.
The principal aim of the project is to reduce youth crime.
The train is intended to ease congestion caused by more than 300,000 cars a day travelling between the province’s two principal cities.
In most circumstances, the police are the principal source of all information that subsequently becomes evidence in a criminal prosecution.
Principal is also noun, and its various noun meanings are linked to the adjectival sense (i.e. ‘most important’). A principal may be the head of a school, college, or other educational institution, the leading performer in a concert, ballet, opera, or play, or the most important person in an organization or group:
As the principal of a small school I know what every child is up to in terms of their academic achievement and their behaviour.
All the principals in the cast deliver vivid, memorable performances.
He is now principal of the Rotterdam-based Office for Metropolitan Architecture.
As a singular noun, principal can also refer to a sum of money lent or invested, on which interest is paid:
She was assured that there would be no risk to her principal.
In the first years in which you pay back your loan, the majority of each payment goes towards interest rather than principal.
There are several other noun senses – see the dictionary entry for more details.
Still not sure about principal vs. principle?
If you’re unsure whether to use principle or principal, try thinking about the context. Generally speaking, a principle is a rule, standard, or belief of one kind or another. As an adjective, principal means ‘most important’, while a principal is – generally speaking – a person who is most important in a particular organization or group.
Take our quiz!
Test yourself with this quick principle vs. principal quiz: