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Principal vs Principle

Definitions​

  • ‘Principal’ (adj) means ‘main; most important’.
  • ‘Principle’ (adj) means ‘a proposition, theorem or idea’.

What’s the difference between ‘principal’ and ‘principle’?​

It is easy to misspell and therefore confuse the two, but they are very different in usage and meaning.

  • ‘Principal’ is an adjective, which combines with nouns like ‘objectives’, ‘components’, ‘measures’, or ‘findings’ in academic texts. It is also frequently used in the phrase ‘principal investigator’ (PI), referring to the lead researcher for a project/main holder of a grant.
  • ‘Principle’ is a noun, and is also frequently used in academic texts due to its scholarly meaning (a proposition, theorem or idea).

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How they’re used​

Example sentences with ‘principal’

  • We introduce an algorithm for producing approximate principal components.
  • They are the principal techniques used to understand outer layers of substrates.

Example sentences with ‘principle’

  • The authors were the first to introduce the principle of relativity.
  • Our paper presents an extension of Banach's contraction principle.