Portable Wireless Hard Drive

Try The Gioi Di Dong.  They're everywhere, recognisable by the yellow and black buildings.  I've seen Seagate Backup Plus in one of their shops.

I'd like to know the official definition of a "wireless hard drive" Wireless usually means no wire at all, good luck with that 

I'm assuming you mean an external hard drive that is USB powered so you don't need a separate power adapter.

Isn't wireless HD the kind that uses either bluetooth or its own built-in WiFi, while the traditional one uses USB?

My Seagate needs USB but Seagate Wireless is, well, wireless.  Originally, I planned to buy the Wireless version, but when I learned that its max storage only reached 500GB at the time (I think the newest one is 2TB now) and its battery lasted only 6 hrs, I opted for the traditional version with 4TB instead.

Well, I'll be damned. Thank you Ciambella, I work in IT but I stand corrected. Wireless hard drives really do exist, with a battery and WiFi chip. 

No I mean a wireless portable hard drive. There are portable hard drives that connect to your device wirelessly. All the major manufacturers of portable hard drives make them eg WD etc.
They are not common but they are available, Tyne largest I have seen is 3tb.
Dave