6
vital(adjective, top, important, significant, original)
5
critical(adjective, original, essential, fundamental, key)
5
implicit in(verb, expression, adjective, phrasal verb)
5
original(adjective, simple, plain, important, significant)
5
subjacent(adjective, lower, beneath)
5
ultimate(adjective, surface)
4
base(adjective, last, bottom)
4
based on
4
central(adjective, top, important, significant, original)
4
constitutional(adjective, important, significant, original, essential)
4
indispensable(adjective, important, significant, original, essential)
4
key(adjective, important, significant, original, essential)
4
latent(adjective, hidden, dormant)
4
main(adjective, top, original, essential, basic)
4
necessary(adjective, important, significant, original, essential)
4
primal
3
capital(adjective, essential, fundamental, key, main)
3
concealed(adjective, fundamental, latent)
3
covert
3
integral(adjective, important, significant, original, essential)
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APASmart Define. (2015). underlying thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/underlying/thesaurus/synonyms
ChicagoSmart Define. 2015. "underlying thesaurus" https://smartdefine.org/underlying/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, underlying thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/underlying/thesaurus/synonyms>.
MLASmart Define. "underlying thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/underlying/thesaurus/synonyms>