: a small, steep waterfall; especially: one that is part of a series of waterfalls. : a large amount of something that flows or hangs down.: a large number of things that happen quickly in a series.ull Definition of CASCADE. intransitive verb. : to fall, pour, or rush in or as if in a cascade. transitive verb. 1. : to cause to fall like a cascade. 2. : to connect in a cascade arrangement.