17
strengthen(verb, support, close, set, fix)
14
brace(verb, support, close, set, fix)
13
harden(verb, support, close, set, increase)
12
fortify(verb, support, close, set, fix)
11
reinforce(verb, support, close, set, fix)
10
temper(noun, verb, close, set, fix)
9
acclimate(verb, close, set, keep, overcome)
9
acclimatize(verb, close, set, fix, continue)
8
anneal(verb, support, close, set, fix)
7
confirm(verb, support, increase, establish, extend)
7
invigorate(verb, support, increase, encourage, establish)
7
season(verb, close, set, keep, overcome)
7
stiffen(verb, support, close, set, fix)
6
indurate(verb, close, set, fix, settle)
6
inure(verb, rough, prepare, strengthen, scratch)
5
accustom(verb, rough, prepare, adjust, scratch)
5
buttress(verb, support, close, set, fix)
5
callous(verb, adjective, close, set, fix)
5
support(verb, increase, establish, extend, sustain)
4
develop(verb, strengthen, scratch, harden, roughen)
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APASmart Define. (2015). toughen thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/toughen/thesaurus/synonyms
ChicagoSmart Define. 2015. "toughen thesaurus" https://smartdefine.org/toughen/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, toughen thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/toughen/thesaurus/synonyms>.
MLASmart Define. "toughen thesaurus" 13 April 2015. Web. 20 September 2026. <https://smartdefine.org/toughen/thesaurus/synonyms>