I suggest consideration for "hi-res" if you want something terse, or "high resolution" if terseness isn't needed.
I agree with Ben Brocka's points about the problems with "@2x" and "retina". But I think "High DPI" is not necessarily accurate because I may provide to 2 images with the same DPI, one is just much more compressed than the other (and it will have lower resolution).
The problem of such high device DPI disparity (HDDPID ;)) is a new one and we're still trying to figure out solutions to it. (Here's an article about that, note they use the term "HIDPI" to refer high pixel density.) I could envision a methodology that uses the same pixel size images for all devices, but a highly compressed version for low DPI devices and a less compressed version for high DPI devices. Both versions are the same DPI but one is higher resolution.
Then again it might be best to refer to the image's targeted device type, in which "High DPI" or "HIDPI" (as used in the linked article) would be appropriate.
In summary, if we are referring to the characteristics of the image I vote for "hi-res" or "high resolution", but if referring to the image's targeted device "HIDPI" or "High DPI". Either way it would be nice to standardize on something.