37 entries under basic topic. ×

19
mandatory(adjective, right, significant, affected, essential)
18
compulsory(adjective, sound, important, certain, true)
16
requisite(adjective, appropriate, proper, significant, suitable)
15
essential(adjective, important, significant, critical)
15
imperative(adjective, important, significant, essential)
15
required(adjective, right, significant, essential)
13
binding(adjective, sound, certain, true, significant)
12
indispensable(adjective, important, significant, essential, critical)
8
prerequisite(adjective, significant, essential, vital)
5
de rigueur(expression, adjective, right, significant, essential)
5
pressing(adjective, important, significant, essential, critical)
5
unavoidable(adjective, certain, significant, essential)
5
urgent(adjective, important, significant, essential, critical)
4
exigent(adjective, important, significant, essential, critical)
4
needful(adjective, significant, essential, vital)
4
vital(adjective, important, significant, essential, critical)
3
compelling(adjective, significant, essential, vital)
3
crucial(adjective, important, significant, essential, critical)
3
needed(adjective, significant, essential, vital)
2
decisive(adjective, significant, essential, vital)
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APASmart Define. (2015). obligatory thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/obligatory/thesaurus/synonyms
ChicagoSmart Define. 2015. "obligatory thesaurus" https://smartdefine.org/obligatory/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, obligatory thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/obligatory/thesaurus/synonyms>.
MLASmart Define. "obligatory thesaurus" 14 April 2015. Web. 20 September 2026. <https://smartdefine.org/obligatory/thesaurus/synonyms>