Re: Forgive my ignorance, but...
A superstrat is a "spongy" term nowadays, but originally it was used to mean hot rodded Strats (Charvels, EVH´s "Frankenstein" and similar guitars).
The only REAL defining characteristic Nowadays seems to be the bridge Humbucker, this is definitely essential. Other Pickups are generally not "necessary" for the title, but H-S, H-S-S, H-H-, H-S-H, H-H-S., et.al. also qualify as superstrats.
IMO a Floyd Rose or V-trrem is also essential, but many consider hardtails as superstrats as well.
I personally don´t consider downsized bodies (Jackson Soloist/ Dinky, Ibanez RG/ S....) to be superstrats, because for me it´s not a Strat, period. But here as well, others do....
But I think that´s about as precise as it gets....
