What is an antonym for the word habit?

There isn't one perfect antonym for "habit" as it depends on the context. Here are some options based on different meanings:

If "habit" refers to a repeated action:

* Occasional

* Infrequent

* Sporadic

* Uncommon

* Rare

* Once-in-a-while

If "habit" refers to a learned behavior:

* Instinct

* Natural tendency

* Unlearned behavior

If "habit" refers to a pattern or routine:

* Spontaneity

* Impulsiveness

* Unpredictability

* Flexibility

If "habit" refers to a negative, ingrained behavior:

* Virtue

* Good habit

* Healthy practice

The best antonym will depend on the specific context and what aspect of "habit" you want to contrast.