150 entries under adjective topic. ×

1
hard-line(strong, hard, tough, severe)
1
indomitable(set, strong, hard, tough)
1
insensible(strong, hard, tough, sturdy)
1
iron-willed(determined, resolute, uncompromising, unshakeable)
1
potent
1
puissant
1
rock-ribbed(determined, resolute, uncompromising, unshakeable)
1
stony-hearted
1
stringent(hard, severe, stiff, resolute)
1
strong-willed(determined, resolute, uncompromising, unshakeable)
1
stubborn as a mule(idiom, resist, firmly)
1
thick(strong, hard, tough, firm)
1
unsparing(strong, hard, tough, sturdy)
1
unswerving(determined, resolute, uncompromising, unshakeable)
1
unsympathetic
0
armored(strong, tough, permanent, strengthened)
0
astringent(strong, hard, tough, sturdy)
0
bad
0
bitter(strong, hard, tough, sturdy)
0
by the book(expression, idiom, strong, hard)
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APASmart Define. (2015). adamantine thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/adamantine/thesaurus/synonyms
ChicagoSmart Define. 2015. "adamantine thesaurus" https://smartdefine.org/adamantine/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, adamantine thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/adamantine/thesaurus/synonyms>.
MLASmart Define. "adamantine thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/adamantine/thesaurus/synonyms>