4
basal(adjective, body, material, important, significant)
4
bathroom
4
expedient(adjective, essential, required, wanted, needed)
4
good(wanted, needed)
4
inerrant(adjective, certain, inevitable)
4
inevasible(adjective, certain, obvious, inevitable, inescapable)
4
lavatory
4
logical(adjective, clear, sound, reasonable, rational)
4
of the essence(expression, adjective, idiom, important, essential)
4
sine qua non(noun, expression, idiom, need, essential)
4
underlying(adjective, important, significant, original, essential)
3
absolute
3
bottom-line(adjective, important, significant, original, essential)
3
bound
3
bounden(required, obligatory, conclusive)
3
called-for(adjective, important, serious, essential, critical)
3
consequential(adjective, important, prominent, exalted)
3
determinate
3
duty(noun, want, essential, obligation, requirement)
3
elemental(adjective, body, material, important, significant)
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APASmart Define. (2015). necessary thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/necessary/thesaurus/synonyms
ChicagoSmart Define. 2015. "necessary thesaurus" https://smartdefine.org/necessary/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2015, necessary thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/necessary/thesaurus/synonyms>.
MLASmart Define. "necessary thesaurus" 2 November 2015. Web. 23 September 2026. <https://smartdefine.org/necessary/thesaurus/synonyms>