Entry Definition
(body part, old motor, etc.) s/he, it starts to lose vitality or power; (gun) it begins not to shoot straight, begins to shoot off-target (usually, because grooves inside barrel are worn or pitted); (tree) s/he starts to bend from old age
it wears out, deteriorates from repeated use
it has deteriorated, is in disrepair, is dilapidated; it is useless
s/he is showing signs of physical and mental decline or deterioration