Fundamentals

fəndəˈmentl
noun
plural noun: fundamentals

  1. a primary rule or principle on which something is based; essential part.

“the courses cover the fundamentals of learning”

  • synonyms: basics, essentials, rudiments, foundations, principles, preliminaries;
  • informal – nuts and bolts, nitty-gritty, brass tacks, meat and potatoes, ABC

“fundamental principles”, “the fundamental structure”
Origin
Latin – fundare – to found