Synonyms for Firm:

adj.

able-bodied (adjective)
powerful, robust.
all (adjective)
stiff, unbendable, solid, strong, unfaltering, unshakable, steadfast, unwavering, steady.
bent (adjective)
settled.
brave (adjective)
fearless.
dense (adjective)
impenetrable.
flinty (adjective)
steely.
hard (adjective)
rigid, stiff, solid, callous, hard.
hardened (adjective)
concrete.
healthy (adjective)
healthy.
inelastic (adjective)
inflexible, immovable, inelastic, rigid, unalterable, stiff, unyielding.
inflexible (adjective)
dense, thick, concrete, sturdy, set, impenetrable, close, compact, tough, condensed, rigid, unyielding, hardened, impervious, substantial, solid, heavy, hard, inelastic, stiff.
liege (adjective)
liege.
resolute (adjective)
dogged, determined, reliable, committed, relentless, tireless, decisive, indomitable, constant, indefatigable, thorough, resolute, tough, zealous, stern, persistent, inexorable, unflinching, spunky, unyielding, strong-willed, set, bold, tenacious, staunch, implacable, diligent, deliberate, insistent, resolved, courageous, plucky, serious, steely, unshakeable, unbending, bullheaded, unchangeable, decided, intent, unwavering, valiant, fearless, ruthless, loyal, steadfast, hearty, steady, earnest, iron-willed, stubborn, willing, persevering, devoted, dauntless, true, faithful, dedicated, strong-minded, uncompromising, headstrong.
rocklike (adjective)
hard.
solid (adjective)
dense, substantial, stable, set, concrete, solid, physical, hard.
stable (adjective)
consistent, durable, changeless, immovable, continuous, invariable, permanent.
stable, unmoving (adjective)
immobile, taut, tight, fixed, tenacious, stationary, durable, sound, fast, secure, motionless, strong, petrified, unfluctuating, fastened, settled, mounted, immovable, robust, rooted, unshakable, steady.
strong (adjective)
mettlesome, iron-willed, formidable, virile, stout, powerful, brawny, energetic, sturdy, husky, stable, tough, muscular, robust, vital, strong, potent, mighty, sinewy, vigorous.
substantial (adjective)
real, meaningful, significant, united, bodily, substantive, substantial, palpable, material, considerable, tangible, sturdy, actual, physical, appreciable, important, immanent, solid.
tight (adjective)
snug, stiff, rigid, tight, secure, dense, tense, taut.
true (adjective)
truehearted.
unalterable, definite (adjective)
established, true, unchangeable, determined, unbending, stable, adamant, specific, consistent, resolute, flat, steadfast, intent, unflinching, constant, resolved, inflexible, explicit, persevering, persistent, unwavering, staunch.

adv

fast (adverb)
steadfastly.

adv.

all (adverb)
steadfastly, firmly, unwaveringly.

n.

unchanging, unvarying, whatever happens, for good, irreversible. affiliate, resist, agency, base, anchor, resolve, the biz, blue-chip, acquisition, big business, account, agent. competitive, ambitious, incompressible, sedulous, driven, motivated. confirm, make certain, underline, crystallize, assure, gel, crystalize, continue. boil over, break down, cloud, boil away, bake, boil up, clear, atomize, boil, bubble. intensify, toughen, strengthen, reinforce, bolster, sharpen, purpose, invigorate. reputable, responsible, as good as your word, decide, dependable. packed, trust, rock-hard, allegiant, liege. change, certain, flat. free, Clinging. business (noun)
company, job, busy work, negotiation, station, venture, activity, enterprise, industry, labor, market, consortium, service, affair, situation, assignment, holding, house, livelihood, merchant, partnership, establishment, position, corporation, practice, selling, employment, career, management, posting, exchange, barter, specialty, business, transaction, retailing, trade, profession, proprietorship, vocation, occupation, calling, concern, interest, commission, commerce.
business concern (noun)
company.
business establishment (noun)
house.
definite (noun)
definite, explicit, specific, confirmed.
firm (noun)
fast, steadfast, firmly, solid, unfaltering, fresh, forceful, tauten, healthy, established, faithful, stable, business firm, steadfastly, unshakable, unwavering, truehearted, hard, crunchy, loyal, immobile, resolute, unbendable, secure, unwaveringly, steady, house, strong, settled, crisp, unfluctuating, fixed.

v.

change (verb)
tauten.
harden (verb)
solidify, harden, stiffen.
hardened (verb)
petrified.
tighten (verb)
stiffen, tense, tighten, secure.

Other synonyms:

mounted, packed, responsible, incompressible, liege. certain. flat. compressed
condensed.
established
established.
firm
motionless.
harden
solidify, harden, toughen.
implanted
rooted.
Other relevant words:
fixed, sound, established, firmly, fast, house, compact, fastened, close, settled, unfaltering, adamant, dependable.

Usage examples for firm

  1. But Mrs. Pell was firm as Rex had been firm – Two Boys and a Fortune by Matthew White, Jr.
  2. He addressed his soldiers in a firm voice, saying: " Soldiers! – The Project Gutenberg Memoirs of Napoleon Bonaparte by Bourrienne, Constant, and Stewarton
  3. They were firm I was firm and so the affair came to nothing. – The Grand Babylon Hotel by Arnold Bennett