4
earnestly(adverb, fast, intensely, fiercely, quickly)
4
faithfully(adverb, absolutely, very, really, thoroughly)
4
forcibly(adverb, fast, fully, intensely, fiercely)
4
hard(adjective, adverb, firm, fast, badly)
4
heavily(adverb, fast, fully, intensely, fiercely)
4
mightily(adverb, strongly)
4
obstinately
4
robustly(adverb, strongly)
4
sharply(adverb, hard, fast, badly, severely)
4
solid(adjective, adverb, severely, strongly, definitely)
4
soundly(adverb, firm, severely, thoroughly, strongly)
4
stalwartly(adverb, powerfully, faithfully, steadfastly, loyally)
4
staunchly
4
steady(adjective, adverb, firm)
4
sternly
4
surely(adverb, absolutely, very, really, exactly)
4
tight(adverb, firm, fast, severely, thoroughly)
4
toughly(adverb, strongly)
4
unalterably(adverb, inelastically)
4
unchangeably(adverb, unalterably)
11 years ago|13k views|share |citing 
APASmart Define. (2015). firmly thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/firmly/thesaurus/synonyms
ChicagoSmart Define. 2015. "firmly thesaurus" https://smartdefine.org/firmly/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, firmly thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/firmly/thesaurus/synonyms>.
MLASmart Define. "firmly thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/firmly/thesaurus/synonyms>