Modal verb

Type of auxiliary verb that is used to indicate modality, such as "might"

A modal auxiliary verb gives information about the function of the main verb that it governs. Modals have a wide variety of communicative functions, but these functions can generally be related to a scale ranging from possibility ("may") to necessity ("must"), in terms of one of the following types of modality:

The following sentences illustrate epistemic and deontic uses of the English modal verb must:

The following table lists the modal auxiliary verbs of standard English and various senses in which they are used:

The verb catenae are in blue. The modal auxiliary in both trees is the root of the entire sentence. The verb that is immediately subordinate to the modal is always an infinitive. The fact that modal auxiliaries in English are necessarily finite means that within the minimal finite clause that contains them, they can never be subordinate to another verb, e.g.,

The English modal verbs share many features and often etymology with modal verbs in other Germanic languages.

In (modern) English, Afrikaans, Danish, and Swedish, the plural and singular forms are identical. For German, Dutch, Low Saxon, West Frisian, Faroese and Gothic, both a (not the) plural and a singular form of the verb are shown. Forms within parentheses are obsolete, rare, and/or mainly dialectal in the modern languages.

Owing to their modal characteristics, modal verbs are among a very select group of verbs in Afrikaans that have a preterite form. Most verbs in Afrikaans only have a present and a perfect form.

In English, modal verbs are called defective verbs because of their incomplete conjugation: They have a narrower range of functions than ordinary verbs. For example, most have no infinitive or gerund.

In many Germanic languages, the modal verbs may be used in more functions than in English. In German, for instance, modals can occur as non-finite verbs, which means they can be subordinate to other verbs in verb catenae; they need not appear as the clause root. In Swedish, some (but not all) modal verbs have infinitive forms. This for instance enables catenae containing several modal auxiliaries. The modal verbs are underlined in the following table.

The Swedish sentence translated word by word would yield the impossible "*he must can do it"; the same goes for the German one, except that German has a different word order in such clauses, yielding "*he must it do can".