Thesaurus.com
Dictionary.com

most established

ADJECTIVE
in a firm position
Synonyms
STRONGEST
entrenched settled traditional well-established
STRONG
fixed ingrained rooted secure set stable vested
WEAK
deep-rooted permanent unshakable
Antonyms
STRONG
indefinite undecided unfixed unstable
WEAK
false insolvent invalidated temporary unsound untrue
ADJECTIVE
set up to endure
Synonyms
STRONGEST
chartered completed founded incorporated initiated organized ratified set up settled
STRONG
begun codified conceived endowed equipped finished inaugurated instituted originated produced realized systematized
Antonyms
STRONG
incomplete unfinished
WEAK
false insolvent invalidated temporary unsound untrue
ADJECTIVE
conclusively proved
Synonyms
STRONGEST
accepted approved closed concluded confirmed endorsed identified
STRONG
achieved ascertained assured authenticated corroborated demonstrated determined guaranteed objectified proved substantiated upheld validated verified
WEAK
certain found out sure undeniable valid
Antonyms
STRONGEST
disapproved
STRONG
uncertain
WEAK
false insolvent invalidated temporary unsound untrue