also POW, initialism for prisoner of war, coined 1919 but not common until World War II.
expression imitative of a blow, collision, etc., first recorded 1881.
An imitation of a blow, collision, explosion, etc, used for sudden emphasis or to show sudden understanding: Suddenly bells went off and I knew that was it! Pow! (1881+)
Power; influence; clout: only be apprehended by government action, that is, by political ''pow'' (1960s+)
[noun sense reinforced by power]