Pertaining to the foundation or basis; serving for the foundation. Hence: Essential, as an element, principle, or law; important; original; elementary; as, a fundamental truth; a fundamental axiom.(adjective)
source: webster1913
noun (n)
any factor that could be considered important to the understanding of a particular business(noun.event)
Example: Fundamentals include a company's growth, revenues, earnings, management, and capital structure.
source: wordnet30
the lowest tone of a harmonic series(noun.cognition)
A leading or primary principle, rule, law, or article, which serves as the groundwork of a system; essential part, as, the fundamentals of the Christian faith.(noun)
Example: The fundamental revolution in human values that has occurred.
The book underwent fundamental changes.
Committed the fundamental error of confusing spending with extravagance.