OHKO 

To be knocked out in one hit.
One Hit Knock Out

He's so powerful he can OHKO anyone he fights now.

OHKO by Bone August 5, 2004

OHKO 

Noun. A "one-hit knock out". To use a move that will entirely deplete the foes health.

Did you see that Thunderbolt wreck that Gyarados? OHKO city.

OHKO by DannyOHKOs January 10, 2017