foundering

(noun) (of a ship) sinking. Synonyms: going under.

(verb) fail utterly; collapse. Synonyms: fall through, fall flat, founder, flop. Example: "The project foundered."

(verb) sink below the surface. Synonyms: founder.

(verb) break down, literally or metaphorically. Synonyms: collapse, fall in, cave in, give, give way, break, founder. Examples: "The wall collapsed." "The business collapsed." "The dam broke." "The roof collapsed." "The wall gave in." "The roof finally gave under the weight of the ice."

(verb) stumble and nearly fall. Synonyms: founder. Example: "The horses foundered."