See basic in Webster's New World Roget's A-Z Thesaurus II
adjective
Of or being an irreducible element:
elemental, elementary, essential, fundamental, primitive, ultimate, underlying. See surfaceConstituting or forming part of the essence of something:
constitutional, constitutive, essential, fundamental, integral, vital. See be, surfaceOf or treating the most basic aspects:
basal, beginning, elementary, rudimental, rudimentary. See simple, startArising from or going to the root or source:
basal, foundational, fundamental, original, primary, radical, underlying. See surface
noun
A fundamental irreducible constituent of a whole:
element, essential, fundamental, rudiment (often used in plural). Idiom: part and parcel. See part
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