It's a goodly place to point out that whereas English has a single -ing form (called present particple or gerund depending on its function, not its form), Latin has two forms: one, a present particple (a verbal adjective), ending in -Vns (e.g., amans), and two, a gerund or a gerundive (both verbal nouns), ending in -Vnd- (amandi, g.s.). Gerundives are also called future passive particples. While present particples are declined in all 5 cases, gerunds lack a nominative form. Here's a famous example of a gerundive: Carthago delenda est (Carthage must be destroyed / C. is to be destroyed). Of a gerundive: aqua utilis bibendo (water good for drinking) from Pliny.