what this word stand for?
 

PTW.

I read forum lot but first time I see PTW, I automatic assume it is some kind of guns then I check to see what it look like. It look like m4, etc. Then I learn that PTW isn't gun but is term for something. But I don't know what it stand for.

Professional Training Weapon.

so it mean that PTW gun has exactly same weight, feeling as real gun?

Guns made by Systema.

The Systema Professional Training Weapon is regarded as one of the highest quality guns on the market, produced for police training and such.

oh, thank lot for explain to me :)

It's a selling phrase systema uses for their insane price tags.

think thats a biased definition of it.
PTW is simply a class of airsoft guns made by Systema.