Whoa
来自Big Physics
late Middle English: variant of ho2.
wiktionary
Whoa (c. 1843) is a variant of woa (c. 1840), itself a variant of wo (c. 1787), from who (c. 1450), ultimately from Middle English ho, hoo(interjection), probably from Old Norse hó!(interjection, also, a shepherd's call). Compare German ho, Old French ho !(“hold!, halt!”).
etymonline
whoa (interj.)
1620s, a cry to call attention from a distance, a variant of who. As a command to stop a horse, it is attested from 1843, a variant of ho. As an expression of delight or surprise (1980s) it has gradually superseded wow, which was very popular in the 1960s.
