3
nerve(verb, close, set, fix, settle)
3
petrify(verb, close, set, fix, settle)
3
starch(verb, close, set, fix, settle)
3
sustain(verb, support, calm, fix, increase)
2
callous(verb, dull, close, set, fix)
2
candy(verb, harden, jellied, thicken, solidify)
2
chill(verb, set, freeze, harden, thicken)
2
close(verb, set, fix, settle, firm)
2
condense(verb, form, set, fix, develop)
2
confirm(verb, encourage, restore, revive, refresh)
2
curdle(verb, close, set, fix, settle)
2
encumber
2
fasten(verb, calm, place, set, fix)
2
gird(verb, close, set, fix, settle)
2
good
2
increase(verb, support, sustain, uphold, strengthen)
2
inflexible
2
intensify
2
numb(verb, dull, develop, rough, adjust)
2
precipitate(verb, close, set, fix, settle)
11 years ago|7.2k views|share |citing 
APASmart Define. (2015). stiffen thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/stiffen/thesaurus/synonyms
ChicagoSmart Define. 2015. "stiffen thesaurus" https://smartdefine.org/stiffen/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, stiffen thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/stiffen/thesaurus/synonyms>.
MLASmart Define. "stiffen thesaurus" 13 April 2015. Web. 25 September 2026. <https://smartdefine.org/stiffen/thesaurus/synonyms>