4
energize(verb, support, increase, sustain, uphold)
4
intensify(verb, support, increase, establish, extend)
4
prop(verb, support, increase, sustain, uphold)
4
steel(verb, support, close, set, fix)
3
acclimatise
3
calcify(verb, close, set, fix, settle)
3
consolidate(verb, support, close, set, fix)
3
discipline(verb, rough, prepare, scratch, harden)
3
endure(verb, keep, overcome, resist, suffer)
3
fossilize(verb, close, set, fix, settle)
3
gird(verb, support, close, set, fix)
3
nerve(verb, close, set, fix, settle)
3
ossify(verb, close, set, fix, settle)
3
petrify(verb, close, set, fix, settle)
3
vitrify(verb, close, set, fix, settle)
2
amalgamate(verb, close, set, fix, settle)
2
bake(verb, close, set, fix, settle)
2
beef up(verb, expression, phrasal verb, support, increase)
2
bolster(verb, support, increase, establish, extend)
2
cement(verb, close, set, fix, settle)
11 years ago|4.3k views|share |citing 
APASmart Define. (2015). toughen thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/toughen/thesaurus/synonyms
ChicagoSmart Define. 2015. "toughen thesaurus" https://smartdefine.org/toughen/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, toughen thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/toughen/thesaurus/synonyms>.
MLASmart Define. "toughen thesaurus" 13 April 2015. Web. 26 September 2026. <https://smartdefine.org/toughen/thesaurus/synonyms>