dyed-in-the-wool in Spanish
dyed-in-the-wool in Spanish
acérrimo
(idiomatic, figuratively, of a person) Firmly established in one's beliefs or habits; having a specified characteristic, identity, etc. deeply ingrained in one's nature.
inveterado
(idiomatic, figuratively, of a person) Firmly established in one's beliefs or habits; having a specified characteristic, identity, etc. deeply ingrained in one's nature.