41
strong(adjective, strain, firmness, distinct, labour)
38
sound(adjective, strain, firmness, labour, hardiness)
36
hard(adjective, strain, firmness, labour, hardiness)
22
substantial(adjective, strain, firmness, labour, hardiness)
19
lasting(adjective, strain, firmness, labour, hardiness)
19
long-standing(adjective, strain, firmness, labour, hardiness)
19
settled(adjective, strain, firmness, labour, hardiness)
18
enduring(adjective, strain, firmness, labour, hardiness)
2
set
2
dyed-in-the-wool
2
good(true, real, indisputable)
1
well-founded
1
absolute(complete, true, fixed, real, indisputable)
1
actual(true, real, indisputable)
1
age-old(adjective, old)
1
ageless
1
classic
1
confirmed
1
deep-dyed
1
deep-rooted
11 years ago|2.7k views|share |citing 
APASmart Define. (2015). well-established thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/well-established/thesaurus/synonyms
ChicagoSmart Define. 2015. "well-established thesaurus" https://smartdefine.org/well-established/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, well-established thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/well-established/thesaurus/synonyms>.
MLASmart Define. "well-established thesaurus" 13 April 2015. Web. 20 September 2026. <https://smartdefine.org/well-established/thesaurus/synonyms>