A person who has smoked for 50 years is an example of someone who would be described as an inveterate smoker.
An inveterate liar.
"none of these Princes do use to maintaine any armies together, which are annex'd and inveterated with the governments of the provinces, as were the armies of the Roman Empire. "
"The foregoing elements of disunion are inveterated by the constituent formation of our national legislature. In the French chambers the members are all Frenchmen ; but our members of Congress are effectively Georgians, New-Yorkers, Carolinians, Pennsylvanians, &c."
Origin of inveterate
From American Heritage Dictionary of the English Language, 5th Edition
- Cognate to Italian inveterato.