to fall down or break completely; to disintegrate

to fall inward and become flat abruptly and completely, e.g. through compression

a collapsed lung

to fail suddenly and completely

to suffer a breakdown in energy, stamina, or self-control through exhaustion or disease; esp to fall helpless or unconscious

to fold down into a more compact shape

a telescope that collapses

to cause (something) to collapse

an instance of collapsing falling down, falling in, or disintegration

total failure or breakdown

a sudden, incapacitating loss of energy, strength, or self-control

an airless state of a lung or part of a lung