In linguistics, the term "gerund" denotes certain types of non-finite verb forms in various languages.

In other languages, it may refer to almost any non-finite verb form; however, it most often refers to an action noun, by analogy with its use as applied to English or Latin.

The word 'gerund' in English comes from the Latin term gerundium, of the same meaning. Gerundium itself comes from the gerundive of the Latin verb gero, gerundus, meaning "to be carried out".

In English, the gerund is identical in form to the present participle (ending in -ing) and can behave as a verb within a clause (so that it may be modified by an adverb or have an object), but the clause as a whole (sometimes consisting of only one word, the gerund itself) acts as a noun within the larger sentence. For example: Eating this cake is easy.

In "Eating this cake is easy," "eating this cake," although traditionally known as a phrase, is referred to as a non-finite clause in modern linguistics. "Eating" is the verb in the clause, while "this cake" is the object of the verb. "Eating this cake" acts as a noun phrase within the sentence as a whole, though; the subject of the sentence is the non-finite clause, specifically eating.