fundamental

(noun) any factor that could be considered important to the understanding of a particular business. Example: "Fundamentals include a company's growth, revenues, earnings, management, and capital structure."

(noun) the lowest tone of a harmonic series. Synonyms: fundamental frequency, first harmonic.

(adj) serving as an essential component. Synonyms: cardinal, central, key, primal. Examples: "A cardinal rule." "The central cause of the problem." "An example that was fundamental to the argument." "Computers are fundamental to modern industrial structure."

(adj) being or involving basic facts or principles. Synonyms: rudimentary, underlying. Examples: "The fundamental laws of the universe." "A fundamental incomatibility between them." "These rudimentary truths." "Underlying principles."

(adj) far-reaching and thoroughgoing in effect especially on the nature of something. Synonyms: profound. Examples: "The fundamental revolution in human values that has occurred." "The book underwent fundamental changes." "Committed the fundamental error of confusing spending with extravagance." "Profound social changes."