"clever person," 1914, probably a special use of whiz "something remarkable" (1908), an extended sense of whizz; or perhaps a shortened and altered form of wizard. Noun phrase whiz kid is from 1930s, a take-off on a radio show's quiz kid.
"make or move with a humming, hissing sound," 1540s, of imitative origin. Meaning "to urinate" is from 1929. Related: Whizzed; whizzing. The noun is recorded from 1610s. Whizzer "something extraordinary" is from 1888.
early 15c., "philosopher, sage," from Middle English wys "wise" (see wise (adj.)) + -ard. Compare Lithuanian žynystė "magic," žynys "sorcerer," žynė "witch," all from žinoti "to know." The ground sense is perhaps "to know the future." The meaning "one with magical power, one proficient in the occult sciences" did not emerge distinctly until c. 1550, the distinction between philosophy and magic being blurred in the Middle Ages. As a slang word meaning "excellent" it is recorded from 1922.
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Harper, D. (n.d.). Etymology of whiz. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/whiz