95 entries under original topic. ×

10
central(adjective, important, significant, essential)
10
indispensable(adjective, characteristic, important, significant, natural)
10
initial(adjective, start, simple, plain, head)
9
critical(adjective, severe, important, essential)
9
crucial(adjective, important, significant, essential)
9
deep-seated(adjective, characteristic, natural, essential)
9
requisite(noun, adjective, important, want, significant)
8
integral(adjective, characteristic, body, material, important)
7
important(adjective, significant, essential, critical)
6
primordial(adjective, important, head, significant, beginning)
5
aboriginal(adjective, pure, head, beginning)
5
beginning(adjective, start, simple, plain, head)
5
bottom(noun, adjective, important, significant)
5
leading(adjective, important, head, significant, beginning)
5
paramount(adjective, important, significant, essential)
5
primeval(adjective, wild, head, beginning)
5
root(noun, adjective, drop, part, material)
4
constitutive(adjective, important, serious, essential)
4
deep(adjective, primary)
3
earliest(adjective, simple, top, rough, opening)
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APASmart Define. (2015). basic thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/basic/thesaurus/synonyms
ChicagoSmart Define. 2015. "basic thesaurus" https://smartdefine.org/basic/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, basic thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/basic/thesaurus/synonyms>.
MLASmart Define. "basic thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/basic/thesaurus/synonyms>