adj. & n.
adj. of, affecting, or serving as a base or foundation, essential, primary, original (a fundamental change; the fundamental rules; the fundamental form).
n. 1 (usu. in pl.) a fundamental rule, principle, or article. 2 Mus. a fundamental note or tone. fundamental note Mus. the lowest note of a chord in its original (uninverted) form. fundamental particle an elementary particle. fundamental tone Mus. the tone produced by vibration of the whole of a sonorous body (opp. HARMONIC). fundamentality n. fundamentally adv.
[ ME f. F fondamental or LL fundamentalis (as FUNDAMENT) ]