9
uncompromising(adjective, tough, firm, difficult, rigid)
7
inflexible(adjective, strong, hard, tough, severe)
7
rigid(adjective, strong, hard, tough, severe)
6
stern(adjective, hard, tough, severe, rough)
6
unyielding(adjective, strong, hard, tough, severe)
5
hardline
5
strict(adjective, strong, hard, tough, severe)
4
inexorable(adjective, strong, hard, tough, firm)
4
tough(adjective, strong, hard, rough, firm)
3
adamant(adjective, strong, hard, tough, rough)
3
firm(adjective, strong, hard, tough, severe)
3
hard-shell(adjective, strong, hard, tough, serious)
3
hard-shelled(adjective, hard, tough, severe, rough)
3
indomitable(adjective, strong, hard, tough, difficult)
3
intractable(adjective, tough, firm, difficult, persistent)
3
relentless(adjective, strong, hard, tough, firm)
3
severe(adjective, strong, hard, tough, rough)
3
steadfast(adjective, firm, persistent, obstinate, insistent)
2
cantankerous(difficult, awkward, persistent, obstinate, stubborn)
2
contrary(difficult, awkward, persistent, obstinate, stubborn)
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APASmart Define. (2015). hard-line thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/hard-line/thesaurus/synonyms
ChicagoSmart Define. 2015. "hard-line thesaurus" https://smartdefine.org/hard-line/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, hard-line thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/hard-line/thesaurus/synonyms>.
MLASmart Define. "hard-line thesaurus" 14 April 2015. Web. 21 September 2026. <https://smartdefine.org/hard-line/thesaurus/synonyms>