12 entries under substantial topic. ×

10
important(adjective, dull, weak, outstanding)
6
significant(adjective, important, critical, meaningful)
5
serious(adjective, false, important, dishonest)
5
big(adjective, slight, poor, thin, important)
4
consequential(adjective, important, small, significant)
4
meaningful(adjective, important, little, meaningless)
4
relevant(adjective, important, insignificant, unrelated)
4
useful(adjective, important)
4
worthwhile(adjective, important, worthless)
3
valuable(adjective, important, inexpensive, priceless)
2
necessary(adjective, important, trivial, essential)
2
worthy(adjective, important)
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APASmart Define. (2016). unimportant thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/unimportant/thesaurus/antonyms
ChicagoSmart Define. 2016. "unimportant thesaurus" https://smartdefine.org/unimportant/thesaurus/antonyms (accessed September 25, 2026).
HarvardSmart Define 2016, unimportant thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/unimportant/thesaurus/antonyms>.
MLASmart Define. "unimportant thesaurus" 28 March 2016. Web. 25 September 2026. <https://smartdefine.org/unimportant/thesaurus/antonyms>