inveterate

Short definition from Wiktionary

Adjective

1. 1
   Firmly established from having been around for a long time; of long standing.
2. 2
   Having had a habit (usually a bad habit) for a long time.
3. 3
   Malignant; virulent; spiteful.

Verb

1. 1
   To fix and settle after a long time; to entrench.