dyed in the wool
Also found in: Acronyms.
Permanent and or firmly established, such as one's opinions. Good luck getting him to listen to your political views—he's a dyed-in-the-wool liberal.
dyed in the wool(of a person) completely and permanently fixed in a particular belief or opinion; inveterate.
If yarn is dyed in the raw state, it produces a more even and permanent colour.