Noun
(chiefly science fiction) A conventional fictional alien from outer space in the form of a small humanoid with green skin.
(humorous) One of the supposed extraterrestrial occupants of UFOs.
(folklore) A type of diminutive sprite or fairy that wears green clothing.
(euphemistic, usually in the plural) A soldier lacking identification as to create uncertainty around their allegiance (most notably employed during the 2010s Ukrainian crisis).
Source: en.wiktionary.org