59 entries under original topic. ×

20
principal(adjective, lead, important, head, significant)
18
fundamental(noun, adjective, important, head, significant)
16
cardinal(noun, adjective, lead, important, head)
14
primary(adjective, lead, important, head, significant)
14
crucial(adjective, important, significant, essential)
12
major(adjective, lead, important, head, significant)
12
prime(adjective, lead, important, head, significant)
10
basic(adjective, important, head, significant, beginning)
5
elementary(adjective, important, head, significant, beginning)
4
underlying(adjective, important, significant, essential)
3
basal(adjective, lead, important, head, significant)
3
elemental(adjective, important, significant, essential)
3
primordial(adjective, important, head, significant, beginning)
3
rudimentary(adjective, important, head, significant, beginning)
2
aboriginal(adjective, head, beginning, opening)
2
intrinsic(adjective, important, significant, essential)
2
predominant(adjective, important, outstanding, significant)
2
primeval(adjective, head, beginning, opening)
2
primitive(adjective, important, head, significant, beginning)
2
requisite(important, significant, essential, critical)
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APASmart Define. (2016). key thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/key/thesaurus/synonyms
ChicagoSmart Define. 2016. "key thesaurus" https://smartdefine.org/key/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, key thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/key/thesaurus/synonyms>.
MLASmart Define. "key thesaurus" 29 March 2016. Web. 22 September 2026. <https://smartdefine.org/key/thesaurus/synonyms>