Where does “grey alien” come from?

grey alien (English) comes from English alien, from Middle English alien, from Old French alien, from Latin aliēnus, from Latin alius, from Proto-Italic aljos, from Proto-Indo-European h₂élyos, from Proto-Indo-European h₂él- — to grow, nourish.

grey alien (English): An archetypical humanoid alien, usually described as having grey skin, elongated, hairless, sexless features, and a large head with bulbous black eyes; chiefly associated with flying saucers, alien abductions and conspiracy theories relating to cover-ups by the United States government, such as Area

Definitions

  1. An archetypical humanoid alien, usually described as having grey skin, elongated, hairless, sexless features, and a large head with bulbous black eyes; chiefly associated with flying saucers, alien abductions and conspiracy theories relating to cover-ups by the United States government, such as Area

Ancestry of “grey alien”, step by step

grey alien traces back through two separate lines of ancestry.

via English alien

StepLanguageWordMeaning
1EnglishalienAny life form of extraterrestrial or...
2Middle EnglishalienAn outsider or foreign person, especially one who...
3Old Frenchalienalien; foreign; non-native; alien
4LatinaliēnusOf that which belongs to another person, place, or object—of another, alien, foreign
5Latinaliusother, another, any other; else; different
6Proto-Italicaljosanother
7Proto-Indo-Europeanh₂élyosother, another
8Proto-Indo-Europeanh₂él-to grow, nourish

via English Grey

StepLanguageWordMeaning
1EnglishGreyA member of the Royal Scots Greys, a cavalry...
2Middle Englishgreygrey, dull, drab; glinting, glistening; grey
3Old Englishgrǣġ
4Proto-West Germanic*grāugrey
5Proto-Germanicgrēwazgrey
6Proto-Indo-Europeanǵʰreh₁-to become green, grow; to grow; to green, to grow
Every word from Proto-Indo-European h₂él-Every word from Proto-Indo-European h₂élyosEvery word from Proto-Italic aljos