Verbs that function as a different part of speech are called verbals. Although we use verbals in our speech constantly, we may not stop to think about the fact that they were originally verbs. Being able to identify these words as verbals -- and not, for example, as verbs -- can help us to figure out how a specific sentence is put together, or how the English language works in general.
A gerund is the noun form of a verb that ends in -ing, such as "smiling" in the sentence, "Smiling makes your face light up." Because a gerund functions as a noun, it can take the place of any position that a noun usually fills in a sentence, such as the subject, direct object, subject complement, or object of a preposition. A gerund can also be combined with other words to create a gerund phrase. In the sentence, "Eating blueberry pie is a messy activity," the word "eating" is a gerund, but it links with "blueberry pie" to become a gerund phrase, all of which is acting as the subject of the sentence.
A participle is the adjectival form of a verb. It ends in -ing, -ed, or another past participle ending (e.g., -en, -d, -t, -n). For example, the word "howling" in the sentence, "I listened to the howling wind" and the word "broken" in the sentence, "My son handed me the broken toy" are both participles. Like other adjectives, participles modify nouns and pronouns. Like gerunds, participles can be used together with other words to make up a participial phrase, such as the first phrase in the sentence, "Howling at the moon, the wolf grieved for his mate."
An infinitive is a verbal in which the verb is preceded by the word "to." For example, in the sentence, "We asked her to teach us about infinitives," the words "to teach" form an infinitive. Like gerunds and participles, infinitives can be part of a phrase, such as the phrase "to knock on the door" in the sentence, "I dared her to knock on the door." Infinitives can be used as nouns, adjectives or adverbs in a sentence.
Other Verbs as Nouns
Although gerunds, participles and infinitives are the three verbals usually discussed, verbs can function as other parts of speech as well. Sometimes verbs are actually used as nouns directly, without any additional suffixes (e.g., "run" in the sentence "Katie went for a run"). Verbs can also function as adjectives or nouns with the addition of suffixes like -ible, -able, or -tion (e.g., accessible, refundable, education).