› [I or T] to become, or cause something to become, full of folds that are not equal in size: This shirt crumples easilyMaking things more or less smooth or straight › [I] If someone's face crumples, it becomes full of lines because of a strong emotion: Her face crumpled with laughter.Laughing and smilingWeeping and crying › [I] If someone crumples, they fall to the ground suddenly: The bullet hit him and he crumpled into a heap on the floor.Falling and droppingMoving downwards