victory
剋 centers on overcoming or defeating something: achieving victory. The single given meaning is straightforward.
剋 combines 克 (overcome) with 刂 (knife), reinforcing the idea of cutting through opposition to achieve victory. The exact historical development is uncertain, but the component relationship is clear.
The outer 克 suggests overcoming, and the inner 刂 is a knife. Picture cutting through obstacles with a blade to secure victory.
For コク, imagine a victorious cock crowing after a fight: cock -> コク, and the knife 刂 helps overcome the opponent.