2
of long standing(expression, idiom)
2
old(adjective, continue, hardened, confirmed, recurrent)
2
ongoing(constant, current, continuous, incessant, long-term)
2
perduring(adjective, constant, lasting)
2
persevering
2
relentless(adjective, steady, persistent, constant, continuous)
2
reliable(adjective, calm, strong, tough, solid)
2
resolute(calm, strong, firm, solid, true)
2
sempervirent
2
set in stone(expression, adjective, idiom, calm, fixed)
2
staunch(calm, strong, firm, solid, true)
2
sturdy(adjective, calm, strong, tough, steady)
2
tenacious(secure, tough, firm, true, fixed)
2
unbroken(adjective, steady, stable, regular, fixed)
2
unerasable
2
unflagging
2
uniform(adjective, calm, strong, secure, firm)
2
unintermitting
2
unswerving
2
upright
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APASmart Define. (2016). permanent thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/permanent/thesaurus/synonyms
ChicagoSmart Define. 2016. "permanent thesaurus" https://smartdefine.org/permanent/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, permanent thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/permanent/thesaurus/synonyms>.
MLASmart Define. "permanent thesaurus" 26 February 2016. Web. 20 September 2026. <https://smartdefine.org/permanent/thesaurus/synonyms>