LOL!
You saw the Yngwie Strat thread, didn't you?
Its what IIRC all the 50's, 60's, and 70's models and before said on the headstocks. Its simply referring to the standard strat vintage tremolo, thats been an all the old strats and new MIM ones.
Yngwie's guitar was designed after a 1968 or 69 Fender Strat, (when CBS bought the Fender Company from Leo Fender, and they switched to the larger "CBS" headstocks that they used thoughout the 70's until 1981 I think.
I guess it means "syncronized" because all the saddles are attatched to the tremolo, so, they all move in unison.
As opposed to say, a bigsby or lyre, or anything like that that was drawn over a Tune-O-Matic (LP, SG, Gibson style bridge) because the saddles didnt move, the strings were yanked behind the saddle, and I suppose NOT syncronized.
It was just a catchword that looked good on the headstock.