The Two Meanings of "Absolute Territory" :
1. A phrase that describes an area of exposed thigh when a girl is wearing a miniskirt and thigh high socks. A fetish most otakus loved.
2. A Japanese short form term for Absolute Terror Field(絶対恐怖領域, Zettai Kyoufu Ryouiki) from Neon Genesis Evangelion.
Origin
Absolute Territory started in 2001, where an A.I based desktop resident chatterbot software called Jinkou Munou was circulating around that time. MIY, the creator of the character Seriko in this software announced his next character called Mayura in his blog. Mayura's costume is designed to have a black turtleneck, a grey checkered miniskirt, black over knee socks and boots. During the announcement, he wrote this comment regarding Mayura :
"The distance between the knee socks and mini skirt is invincible! I can even say that it's God's Absolute Territory."
5 days later, he explained the concept of Absolute Territory even further with the illustrations released on his blog, spreading the term from there.