60 entries under fundamental topic. ×

7
prime(adjective, body, material, important, significant)
5
central(adjective, important, significant, original, essential)
5
demand(noun, want, need, essential, certainty)
5
desideratum(noun, want, need, essential, certainty)
5
elementary(adjective, easy, important, significant, original)
5
integral(adjective, body, material, important, significant)
5
necessitous(adjective, important, capital, essential, vital)
5
primary(adjective, body, material, big, important)
5
want(noun, verb, need, essential, certainty)
4
basal(adjective, body, material, important, significant)
4
underlying(adjective, important, significant, original, essential)
3
bottom-line(adjective, important, significant, original, essential)
3
elemental(adjective, body, material, important, significant)
3
intrinsic(adjective, important, significant, original, essential)
3
primitive(adjective, body, material, important, significant)
2
bottom(adjective, important, significant, original, essential)
2
capital(adjective, important, serious, essential, critical)
2
core(original, key, main, chief)
1
coal-and-ice(important, essential, critical, basic)
1
compulsion(noun, want, need, essential, certainty)
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APASmart Define. (2015). necessary thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/necessary/thesaurus/synonyms
ChicagoSmart Define. 2015. "necessary thesaurus" https://smartdefine.org/necessary/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, necessary thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/necessary/thesaurus/synonyms>.
MLASmart Define. "necessary thesaurus" 2 November 2015. Web. 27 September 2026. <https://smartdefine.org/necessary/thesaurus/synonyms>