Where does “Billyjean” come from?

Billyjean (English) comes from English Billy, from English Bill, from Middle English bill, from Old English bil, from Frankish billi, from Proto-Germanic bilją, from Proto-Germanic harjaz, from Proto-Indo-European kóryos — army.

Ancestry of “Billyjean”, step by step

Billyjean traces back through two separate lines of ancestry.

via English Billy

StepLanguageWordMeaning
1EnglishBillyThe B-25 twin-engine bomber aircraft used during World War Two, commonly called the "B-25 Mitchell" in honor of U.S. Army General William "Billy" Mitchell
2EnglishBillA nickname for the British constabulary. Often called "The Bill" or "Old Bill"
3Middle Englishbill
4Old Englishbila kind of sword or other bladed weapon,...
5Frankishbilli
6Proto-Germanicbiljąa cutting implement; blade; axe; sword; spike;...
7Proto-Germanicharjazarmy; army leader; commander; warrior
8Proto-Indo-Europeankóryoswar; troops; army; war, troops
9Proto-Indo-Europeanḱer-to grow, to make grow, to nourish; to plait,...
10Proto-Indo-Europeankr̥-to turn, to bend
11Proto-Indo-Europeanker-army

via English Jean

StepLanguageWordMeaning
1EnglishJeanDenim
2EnglishJeanne
3FrenchJeanneJane, feminine of John
4Old FrenchJehane
5Medieval LatinJohanna
6LatinJoanna
7Ancient GreekἸωάννα
8Hebrewיוֹחָנָה
9HebrewיוֹחָנָןGod is gracious
10HebrewיְהוֹחָנָןGod is gracious
Every word from Proto-Indo-European ker-