To reduce.
To cause to fall down, e.g. in an accident.
To make something, especially something flying, fall to the ground, usually by firing a weapon of some kind.
To make someone feel bad emotionally.
To make a ruler lose their position of power.
To cause an opponent to fall after a tackle.
To humble.
To reduce emphasis.
To reduce the stresses in a material.
To reduce the stress in oneself or another person.