it's basically the space of skin between a girl's miniskirt and higher-than-the-knee thighs.
coming from the japanese phrase, "絶対領域" (zettai ryoiki), it was first a slang coined up by otakus.
now it's used in japan pretty commonly by the public.
it's also a way to tease guys, since they normally like that more that full nudity.
a good example of where this term is used is in the anime, ナナマル サンバツ (nana
maru sau batsu), meaning "fastest finger first," by character
mari fukami (深見 真理).
*testing
shiki on random quiz terms*
mari : "then.. how about questions like this..? here/"
shiki : "
uee?~"
mari : "Q: the are of exposed skin between the hem of a miniskirt and the tops of knee-high socks is known by what name?"
shiki : t-there's a name for that?
mari : "as i suspected, you like books, but you're not an otaku."
shiki : "wh-what's the answer?"
mari : "
abso..
lute....
terr.. ito.. ry."
*and starts to explain how it's connected to moe culture.*
*shiki
start's entering absolute territory into his dictionary device*
mari : "you won't find it."