gerund – English noun declension

Noun: gerund

Singular	gerund
Plural	gerunds

Compounds in which gerunds are the second element look exactly like compounds in which present participles are the second element, but different principles of hyphenation apply. [1991, Edward Johnson, The Handbook of Good English, page 208:]
Like any noun, the gerund functions as a subject, direct object, indirect object, object of the preposition, or predicate nominative. The gerund phrase is made up of the present participle ("-ing") and can contain an object and/or a modifier (and sometimes many modifiers). The gerund is a verbal noun. [2002, Dan Mulvey, Grammar the Easy Way, page 25:]
Gerunds and gerund phrases are always nouns, so they are always predicate nominatives when used as complements. Do be careful to distinguish progressive-tense verbs from gerunds used as subjective complements. [2005, Gary Lutz, Diane Stevenson, The Writer's Digest Grammar Desk Reference, page 55:]
The Spanish gerund is quite unlike the English -ing form (‘walking’, ‘replying’, ‘saying’, etc.), which can function as a gerund, a present participle, a noun or an adjective; and it is also unlike the French form ending in -ant, which covers the functions of both the Spanish gerund and the adjectival form in -ante, -(i)ente discussed at 19.4. [2013, John Butt, Carmen Benjamin, A New Reference Grammar of Modern Spanish, Kindle edition, Routledge, →ISBN:]

Learned borrowing from Latin gerundium, from gerendus (“which is to be carried out”), future passive participle (gerundive) of gerō (“carry, bear”).

Finnish Nouns gerundi.

English noun forms of gerund