There are various antonyms for the phrase "was habit of," depending on the context in which it is used. Common antonyms for "was" include "was not", "is", "will be", and "has been." When the phrase is used in the sense of an ingrained behavior, antonyms could include "unfamiliar with", "unaccustomed to", "novelty," or "irregular." In contrast, one might use "fluke," "aberration," or "anomaly" when referring to an action that deviates from an existing habit. Regardless of the antonym's context, it reflects a reversal or contradiction of the prior statement's message, suggesting a change from the way things were previously understood.