An adverb is a word or phrase that usually describes a verb, an adjective, another adverb, a determiner, a clause, a preposition, or a sentence. Adverbs often answer questions like how, where, when, how often, to what degree, or how certain something is. This is known as the adverbial function, and it can be carried out by a single adverb, an adverbial phrase, or an adverbial clause.

Adverbs are traditionally considered one of the parts of speech. However, modern linguists observe that the term "adverb" is sometimes used as a general category for words that do not fit neatly into other groups, such as nouns, adjectives, or prepositions. These words may have different roles in a sentence but are grouped together because they do not belong elsewhere.

Functions

The English word adverb comes from the French word adverbe, which in turn comes from the Latin word adverbium. This Latin word is made up of ad- (meaning "to"), verbum (meaning "word" or "verb"), and the suffix -ium (used to form nouns). The word adverb suggests that adverbs mainly act as modifiers, or words that change the meaning of other words. When used this way, adverbs can describe how, where, when, how often, how certain something is, or other details about the action shown by a verb or verb phrase. Examples include:

Adverbs can also change the meaning of adjectives and other adverbs, often to show degree or intensity. Examples include:

They can also change the meaning of determiners, prepositional phrases, or entire clauses or sentences, as shown in these examples:

Adverbs have many roles as modifiers. The main exception is that adverbs usually do not modify nouns. Instead, adjectives are used for this purpose. For example, in "she sang loudly" the adverb loudly modifies the verb sang, while in "her loud singing disturbed me" the adjective loud modifies the noun singing. However, some adverbs and adjectives are homonyms, meaning they are spelled and pronounced the same but have different meanings. For example:

In the first sentence, the word even is an adjective because it comes before the noun numbers and describes it. In the second sentence, the word even is an adverb because it comes before the verb drank and describes how the action was done.

Although adverbs can appear before or after a noun or noun phrase, they do not modify the noun in these cases. For example:

In the first sentence, Internationally is an adverb that comes before the clause "there is…" and modifies it. In the second sentence, internationally is an adverb that comes after the clause "there is…" and modifies it. In contrast, the third sentence uses international, an adjective that comes before the noun shortage and modifies it.

Adverbs can sometimes act as predicative expressions, which describe a situation. In English, this is especially true for adverbs of location:

When an adverb is made up of more than one word, it is called an adverbial phrase or adverbial clause. It is also sometimes simply called an adverbial.

Formation and comparison

In English, adverbs that describe how something happens (called adverbs of manner) are often made by adding -ly to adjectives. However, some adverbs, called flat adverbs, have the same form as their corresponding adjectives. For example, in phrases like "drive fast," "drive slow," and "drive friendly," the words "fast," "slow," and "friendly" act as both adjectives and adverbs. Other languages, such as French, often use different methods to form adverbs from adjectives, like adding the suffix -ment. In German and Dutch, adjectives and adverbs can sometimes share the same form. For example, the word "schnell" in German and "snel" in Dutch can mean either "quick" or "quickly," depending on the context. Many adverbs, though, are not connected to adjectives. These adverbs may come from other words or phrases, or they may be single words. Examples in English include "here," "there," "together," "yesterday," "aboard," "very," and "almost."

When possible, adverbs can be compared using comparative and superlative forms. In English, this is usually done by adding "more" and "most" before the adverb, such as "more slowly" and "most slowly." However, a few adverbs, like "well," use different forms for comparison, such as "better" and "best."

For more details about how adverbs are formed and used in English, see "English adverbs." For information about adverbs in other languages, refer to the section "In other languages" below, as well as the articles about specific languages and their grammar rules.

As a "catch-all" category

Adverbs are a part of speech in traditional English grammar and are still taught in schools and included in dictionaries. However, modern grammarians note that words usually grouped as adverbs can serve many different roles. Some describe adverbs as a "catch-all" category that includes words not classified as other parts of speech.

A logical way to classify words is by identifying which words fit into specific sentence structures. For example, only a noun can complete the sentence template: "When [blank]…"

Using this method, adverbs are found to have multiple categories. Some adverbs modify entire sentences, while others do not. Even when an adverb modifies a whole sentence, its meaning may differ from when it modifies a single word. For example, in the sentences "She gave birth naturally" and "Naturally, she gave birth," the word "naturally" has different meanings: in the first sentence, it modifies a verb and means "in a natural way," while in the second sentence, it modifies the whole sentence and means "of course."

Words like "very" provide another example. The sentence "Perry is very fast" is correct, but "Perry very won the race" is not. These words modify adjectives but not verbs. In contrast, words like "here" and "there" do not modify adjectives. The sentence "The sock looks good there" is correct, but "It is a there beautiful sock" is not. The fact that many adverbs can perform multiple roles may make it seem like splitting hairs to say a single adverb has different functions. However, recognizing these differences can help clarify meanings, especially for words like "naturally" that change meaning depending on their use. Rodney Huddleston distinguishes between a word and a lexicogrammatical-word.

Grammarians have difficulty categorizing negating words, such as the English word "not." Although traditionally listed as an adverb, this word behaves differently from other adverbs and may belong to a separate category.