In traditional grammar, adverb was a catch-all category for everything that was difficult to analyze. Unfortunately, this had the effect of making the category heterogeneous. Some words that are traditionally called adverbs show very different distributions from other words in the same caategory. In some cases, we will not categorize these words as adverbs at all. We will note such cases as they occur in later chapters. We will begin, however, with the most obvious cases.

Adverbs are characteristically used to modify verbs. That is, they perform the same function for verbs that adjectives do for nouns. And indeed, adjectives and adverbs are often closely related, but they do not appear in the same function:

Modifying Nouns Modifying Verbs
adj. new cars *They new drove.
adv. *a suddenly change It changed suddenly.

Many adverbs can also modify adjectives, and some can also modify words of other categories (except nouns), as well as complete phrases and clauses.

verb modifier: The pedestrian appeared suddenly.
adj. modifier: The suddenly hazardous situation took us by surprise.
clause modifier: Suddenly, the pedestrian stepped into the street.

verb modifier: I almost wrecked the car.
adj. modifier: His confusion was almost comical.
adv. modifier: She almost never misses a meeting.
prepositional phrase modifier: The situation was almost beyond repair.

(Note: if you're having trouble seeing why these adjectives and adverbs are modifying the things that I say they are, you might want to read the chapter on phrase structure, and then return to this section.)

Morphologically, many adverbs are formed from adjectives by adding the suffix –ly. Like adjectives, they are also frequently gradable, and can use the comparative and superlative. The very test also works for adverbs.

(20) She exercises very frequently.