Definition of extremly masculine power.
Raw testosteronic power, quite unmatched.
The origin of the expression is the sound you make when something compleatly blows your mind and leaves you speechless; "Ompf...".
Some say that it's the word that comes out when the classical OMFG just ain't enough so you just blurr the rest in total amazement.
"this badass motorcycle packs quite a lot of, you know, ompf!" or "Damn! You killed that raging boar only using your genitels! Ompf man!