settled or confirmed in a habit, practice, feeling, or the like: an inveterate gambler.
2.
firmly established by long continuance, as a disease, habit, practice, feeling, etc.; chronic.
Origin: 1375–1425; late Middle English < Latin inveterātus (past participle of inveterāre to grow old, allow to grow old, preserve), equivalent to in-in-2 + veter- (stem of vetus) old + -ātus-ate1; compare veteran
1528, from L. inveteratus "of long standing, chronic," pp. of inveterare "become old in," from in- "in, into" + veterare "to make old," from vetus (gen. veteris) "old" (see veteran).