cascade

(noun) a small waterfall or series of small waterfalls.

(noun) a succession of stages or operations or processes or units. Examples: "Progressing in severity as though a cascade of genetic damage was occurring." "Separation of isotopes by a cascade of processes."

(noun) a sudden downpour (as of tears or sparks etc) likened to a rain shower. Synonyms: shower. Examples: "A little shower of rose petals." "A sudden cascade of sparks."

(verb) rush down in big quantities, like a cascade. Synonyms: cascade down.

(verb) arrange (open windows) on a computer desktop so that they overlap each other, with the title bars visible.