1
homogeneous(adjective, continuous)
1
hydrophyte
1
immemorial(lasting, permanent, everlasting, unending, undying)
1
in for the long haul(expression, idiom, stable, enduring, lasting)
1
inbred(persistent, continuous, hardened, lasting, continuing)
1
incurable(persistent, continuous, hardened, lasting, continuing)
1
indeciduous
1
indefatigable(adjective, continuous)
1
indefinite(lasting, permanent, everlasting, unending, undying)
1
indelible(adjective, permanent, long-term, lifelong)
1
indissoluble(permanent, everlasting, eternal, long-term, undying)
1
ineradicable(adjective, persistent, continuous, hardened, lasting)
1
inexhaustible(permanent, long-term, lifelong)
1
inexpungible(permanent, long-term, lifelong)
1
ingrained(persistent, continuous, hardened, lasting, continuing)
1
intransitive
1
invariably
1
joined
1
jointless
1
level(adjective, continuous)
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APASmart Define. (2015). perennial thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/perennial/thesaurus/synonyms
ChicagoSmart Define. 2015. "perennial thesaurus" https://smartdefine.org/perennial/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2015, perennial thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/perennial/thesaurus/synonyms>.
MLASmart Define. "perennial thesaurus" 10 April 2015. Web. 29 September 2026. <https://smartdefine.org/perennial/thesaurus/synonyms>