85 entries under tough topic. ×

1
rigorous(adjective, strong, hard, severe)
1
rough(adjective, strong, hard, harsh)
1
self-willed(difficult, wild, awkward, obstinate)
1
serious(adjective, strong, hard, severe)
1
steely(adjective, strong, hard, severe)
1
stiff-necked(adjective, strong, hard, severe)
1
sturdy(adjective, strong, hard, rugged)
1
undisciplined(difficult, wild, awkward, obstinate)
1
unpliable(difficult, wild, awkward, obstinate)
1
unrelenting(adjective, strong, hard, severe)
1
unsparing(adjective, strong, hard, severe)
0
dense(adjective, strong, hard, sturdy)
0
ferric(adjective, strong, hard, sturdy)
0
ferrous(adjective, strong, hard, sturdy)
0
hardboiled(adjective, firm, immovable, hard-nosed)
0
heavy(adjective, strong, hard, sturdy)
0
insensible(adjective, strong, hard, sturdy)
0
robust(adjective, strong, hard, sturdy)
0
rugged(adjective, strong, hard, sturdy)
0
steel(adjective, strong, hard, sturdy)
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APASmart Define. (2015). hard-line thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/hard-line/thesaurus/synonyms
ChicagoSmart Define. 2015. "hard-line thesaurus" https://smartdefine.org/hard-line/thesaurus/synonyms (accessed September 30, 2026).
HarvardSmart Define 2015, hard-line thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/hard-line/thesaurus/synonyms>.
MLASmart Define. "hard-line thesaurus" 14 April 2015. Web. 30 September 2026. <https://smartdefine.org/hard-line/thesaurus/synonyms>