Yo
来自Big Physics
natural exclamation: first recorded in late Middle English.
wiktionary
From Middle English yo, io, ȝo, yeo, yaw, variant forms of ya, ye(“yes, yea”), from Old English ġēa(“yes, yea”), from Proto-Germanic *ja(“yes”), from Proto-Indo-European *yē(“already”); or perhaps from Old English ēow(“Wo!, Alas!”, interjection). Compare Danish, Swedish, Norwegian jo(“yes”), Dutch jow(“hi, hey”) and Dutch jo(“hi, hey”). More at yea, ow, ew.
From you're, your, etc.
yo
From Russian ё(jo).
yo
etymonline
yo
as a greeting, 1859, but the word is attested as a sailor's or huntsman's utterance since early 15c. Modern popularity dates from World War II (when, it is said, it was a common response at roll calls) and seems to have been most intense in Philadelphia.
