When a person is settled in habit, it means that they have developed a routine or a consistent pattern of behavior. Other ways to describe this state could include being established, entrenched, ingrained, accustomed, or accustomed to doing something. One might also say that they have formed a habit of doing something without even thinking about it, or have become fixed in their ways. Still, other synonyms for settled in habit could include being committed to a certain way of doing things or being set in one's ways. Whatever the description might be, it is clear that when a person is settled in habit, change can be very difficult.