To refuse, decline, or deny.
To reduce the power, etc. of something by means of a control, such as the volume, heat, or light.
To reposition by turning, flipping, etc. in a downward direction; to double or fold down.
To decline, to refuse to do or accept.
To contradict or deny.
To forbid, to refuse to allow, give, or permit.
To gainsay, to oppose in speech (and by extension writing).