In linguistics, and in particular the context of grammar, a gerund is a present participle verb which acts as a noun by adding -ing to the end. Some grammarians, however, refer to these as verbal nouns ending in -ing, for example Sidney Greenbaum in An Introduction to English Grammar (1991).

For example:

The term "gerund" is sometimes used incorrectly to mean any word ending with "ing". For example:

  • Jane was swimming in the sea. (The participle verb here functions as an adjective and is not a true gerund.)