main
adjective/pɾĩˈsipau/high
prin·ci·pal
Definitions
1Most important or primary in a given context.
The main topic of the meeting was security.
She is the main author of the project.
2Referring to the head of a school or institution.
The principal of the school gave a speech.
She is the principal of a public school.
3Referring to the capital of a loan or investment.
The principal of the loan must be paid in five years.
The principal of the investment is guaranteed.
Etymology
Do latim 'principalis'