Inveterate means having a habit so long fixed that it will never change. An inveterate gambler, an inveterate liar, inveterate hostility.
It goes with the habit rather than the act, so it is the person who is inveterate. The Latin is grown old, which is exactly what a habit of that kind has done.
1adjectiveinveterateHaving a habit so long fixed it will never change.
“He was an inveterate collector of maps he would never use.”
inveterate is a quality.
Latin inveteratus means grown old or long established, from in plus vetus, old.
Latin
inveterātus — of long standing, chronic
English, today
inveterate
Built from
The adjective is first attested in 1528, the verb in 1574; Latin inveterātus (“of long standing, chronic”), perfect passive participle of inveterō and participial adjective (see -ate and -ate), from in- (“in, into”) + veterō (“to age”), from vetus (“old”). Cognate with Italian inveterato, French invétéré. by surface analysis, in- + veterate.
Etymology from Wiktionary, CC BY-SA