78 entries under basic topic. ×

4
underlying(adjective, important, significant, original, essential)
3
basal(adjective, lead, important, head, significant)
3
elemental(adjective, important, significant, original, essential)
3
name(verb, important, essential, critical)
3
primordial(adjective, important, head, significant, beginning)
3
rudimentary(adjective, important, head, significant, beginning)
2
absolute(adjective, significant, critical, fundamental)
2
intrinsic(adjective, important, significant, original, essential)
2
nub(adjective, absolute, fundamental, central)
2
original(adjective, important, head, significant, beginning)
2
primitive(adjective, important, head, significant, beginning)
2
requisite(important, significant, original, essential, critical)
1
axiological(important, significant, original, vital)
1
axiomatic(important, significant, original, vital)
1
bottom(important, significant, original, vital)
1
bottom-line(important, significant, original, essential, critical)
1
coal-and-ice(important, essential, critical, fundamental)
1
constitutional(adjective, important, significant, original, essential)
1
deep-seated(adjective, original, essential, absolute)
1
foundational(important, significant, original, vital)
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APASmart Define. (2016). key thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/key/thesaurus/synonyms
ChicagoSmart Define. 2016. "key thesaurus" https://smartdefine.org/key/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, key thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/key/thesaurus/synonyms>.
MLASmart Define. "key thesaurus" 29 March 2016. Web. 21 September 2026. <https://smartdefine.org/key/thesaurus/synonyms>