27 entries under serious topic. ×

4
marked(adjective, clear, see, substantial)
4
memorable(adjective, unusual, important, famous, exceptional)
4
remarkable(adjective, great, see, unusual, important)
3
pronounced(adjective, clear, see, substantial)
2
red-letter(adjective, great, extraordinary, unusual, important)
2
rubric(great, extraordinary, unusual, outstanding)
2
striking(adjective, clear, see, unusual, attractive)
1
big-league(great, extraordinary, outstanding, prominent)
1
bodacious(great, extraordinary, unusual, outstanding)
1
celebrated(great, extraordinary, outstanding, prominent)
1
eminent(adjective, unusual, outstanding, prominent)
1
eventful(great, extraordinary, unusual, outstanding)
1
heavy(adjective, great, extraordinary, unusual, important)
1
high-profile(adjective, great, unusual, important, famous)
1
major-league(adjective, great, extraordinary, unusual, important)
1
momentous(unusual, outstanding, prominent, notable)
1
nameable(adjective, great, unusual, important, famous)
1
something else(expression, adjective, unusual, important, famous)
1
top-drawer(great, extraordinary, unusual, outstanding)
1
unusual(adjective, great, extraordinary, important, famous)
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APASmart Define. (2015). observable thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/observable/thesaurus/synonyms
ChicagoSmart Define. 2015. "observable thesaurus" https://smartdefine.org/observable/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2015, observable thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/observable/thesaurus/synonyms>.
MLASmart Define. "observable thesaurus" 10 April 2015. Web. 23 September 2026. <https://smartdefine.org/observable/thesaurus/synonyms>