24 entries under extremely significant topic. ×

20
momentous(adjective, importance, important, main)
16
significant(adjective, importance, important, main, remarkable)
13
notable(adjective, importance, main, remarkable, momentous)
11
consequential(adjective, importance, important, main, remarkable)
11
outstanding(adjective, importance, main, remarkable, momentous)
9
big(adjective, importance, important, main)
9
substantial(adjective, importance, important, main)
9
material(adjective, importance, important, main)
9
meaningful(adjective, importance, important, main)
9
serious(adjective, importance, important, main)
9
weighty(adjective, importance, main)
8
great(adjective, importance, main)
8
impressive(adjective, importance, main)
8
considerable(adjective, importance, important, main)
8
key(adjective, importance, important, main)
8
vital(adjective, importance, important, main)
7
big-league(adjective, importance, main)
7
essential(adjective, importance, main)
7
fateful(adjective, importance, main)
7
grand(adjective, importance, main)
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APASmart Define. (2016). historic thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/historic/thesaurus/synonyms
ChicagoSmart Define. 2016. "historic thesaurus" https://smartdefine.org/historic/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, historic thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/historic/thesaurus/synonyms>.
MLASmart Define. "historic thesaurus" 29 March 2016. Web. 24 September 2026. <https://smartdefine.org/historic/thesaurus/synonyms>