A verb is one of the parts of speech in English language. Verbs can be defined as any word that describes an action, occurrence, or state of existence. Some examples of verb are dance, sing, walk, play, run, sit, habit, etc.
An adverb can be defined as a word that is used in English language to modify a verb, adjective, or another adverb. Some examples are slowly, quickly, brightly, sadly, etc.
When an adverb is used to refer to a whole sentence in order to express an opinion, describe an attitude or simply act as a comment, it is known as a sentence adverb. Some examples of this type of adverb are however, clearly, sadly, evidently, fortunately, seriously, curiously, actually, presumably, apparently, etc.
Furthermore, the adverbial form of a word is usually formed by the suffix "ly" to a verb.
Hence, the adverbial form of the word "habit" is habitually. This simply means an action that is performed regularly, frequently or usually i.e in a habitual manner.