In linguistics, the verbal noun turns a verb into a noun and corresponds to the infinitive in English language usage. In English the infinitive form of the verb is formed when preceded by to, e.g. to sell; but Natural languages may have one or more grammatical process for forming a noun from a verb.
In many languages that have an infinitive, such as English, the infinitive form of a verb can be used as a noun; in English, this use is known as the "supine" or "to-infinitive", in which the bare infinitive is preceded by the particle to:
In English, the supine functions as a mass noun. The English supine is a non-finite verb, that is, it cannot be inflected to mark person or tense. While it cannot have a grammatical subject, it may take an object: "His greatest desire was to serve his country."
When languages have a second grammatical process for forming verbal nouns, it is often called the gerund. In English, the gerund is formed by the ending -ing:
This form is more flexible in its use; for example, it can be used as a count noun: "Most verses of the psalm have multiple readings." Like the supine, the English gerund is a non-finite verb.
The terms "supine" and "gerund" are taken from Latin grammar, in which they also denote verbal nouns, which however differ in many aspects from the correspondingly named English constructions. The variety of verbal nouns across languages does not allow for a unified treatment.
Many nouns that are derived from verbs do not fall under the category of verbal nouns. For example, although the noun "discovery" was formed from the verb "discover", it is not generally classified as a verbal noun. The reason is that its formation is not productive; that is, it is not an instance of a general grammatical process, as shown by the fact that there is no noun "uncovery" formed from the verb "uncover".
In other languages (e.g. Latin), a broader concept of verbal noun is used:
With this definition, "discovery" is a verbal noun as its subject and object might be "the discovery of America by Columbus". In Latin, the nouns "Columbus" and "America" would be in the genitive case to emphasize the fact that they are subject and object of another noun.
With this rule also, nouns like "love" are verbal nouns (e.g. the love for nature) even though the formation from "to love" cannot generally be applied to all nouns (e.g. there is no such word as "a *discover").