ぐる

Etymology 1
Almost certainly derived from verb, with similar derivatives:
 * , attested from the 1150s
 * , attested from the late 900s
 * , attested from 1907

Compare also likely-related noun.

Root

 * 1) rotating, spinning, turning

Etymology 2
Originated as a or  argot word, from the sense of a (usually criminal) ring that metaphorically goes.

Noun

 * 1)   accomplice, co-conspirator

Etymology 3
Shortening of, a hairstyle during the wherein the hair is simply wound up (guruguru) and pinned on top of the head in a bun.

Noun

 * 1)   the bun hairstyle

Etymology 4
Shortening and shift from, from the way that an winds around the body.

Noun

 * 1)   an obi