As with other parts of speech, we can identify verbs based on their inflectional morphology, derivational morphology, and syntactic distribution.

In terms of inflectional morphology, nouns may inflect for tense, aspect, mood, evidentiality, transitivity, polarity, and argument agreement. In English, verbs inflect for tense and subject agreement. The English verbal system also indicates aspect, mood, voice, and polarity through periphrasis, which means the inflectional values are indicated through multiple words, rather than all on one word.

There are many different kinds of derivational morphemes that modify verbs. Some examples of derivational morphemes in English are shown below in (1).

In terms of syntactic distribution, verb phrases are typically the predicate of a clause. The distribution of verb phrases can be described with reference to the subject and tense markers. In English, the verb (in bold) appears after the subject (1a), modals (1b), auxiliaries (1c), and/or the non-finite marker to (1d).

(1) a. Jan ate an apple.

b. Jan will eat an apple.

c. Jan is eating an apple.

d. Jan wants to eat an apple.

Verbs can be modified by adverbs, noun phrase objects, and adpositional phrases, and so their syntactic position can also be described with reference to these. In English, verbs come before objects (2a) and prepositional phrases (2b). Adverbs can appear on either side of the verb phrase in English (2c)-(2d).

(2) a. I saw a movie.

b. I went to the store.

c. I often eat apples.

d. I sleep regularly.

Inflectional values on verbs

We will give a brief overview of some inflectional values that appear on verbs in this section, and go more in depth in the next chapter.

Tense

Tense refers to when the event described by the verb phrase takes place. The main tense categories are past, present, and future, but some languages also have remote and/or recent tense distinctions.

Aspect

Aspect refers to the internal time structure of the event. Some common aspectual distinctions include whether the event is complete (perfective) or incomplete (imperfective), whether the event is continuous (progressive), or whether the even happens repeatedly (habitual).

Mood

Some sentences refer to events or states that have actually happened or are happening, while others indicate things like hypotheticals, alternatives to fact, predictions, and uncertain situations. We can distinguish between these different kinds of situations through mood. The two main broad categories of mood include realis mood—events and states that have actually occurred—and irrealis mood—those which have not actually occurred. Cross-linguistically, there are many different strategies for indicating mood.

Evidentiality

Evidentiality indicates how the information encoded in the sentence is known by the speaker or signer. English does not make use of any evidential markings.

Transitivity

In some languages, verbs may inflect to indicate whether they are transitive or intransitive. In addition, some verbal inflection may indicate a change in the argument structure of the verb. The English passive is an example of inflection that indicates a change in argument structure.

Polarity

Polarity refers to whether the clause is positive or negative. In English, positive sentences are unmarked while negative sentences are marked with the word not or the inflectional morpheme n’t.

Agreement

In some languages, verbs will agree in person and/or number with one or more of its arguments.

Derived verbs

The most common way to derive verbs is from other verbs, as shown in Table X.

There are also some derivational morphemes that create verbs out of nouns and adjectives, as shown in Tables X and X, but they are less common. English typically uses conversion to create denominal verbs, when a verb changes part of speech without morphological changes.

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