"Schmuck", or "shmuck", in American English is a pejorative term meaning one who is stupid or foolish, or an obnoxious, contemptible or detestable person. The word came into the English language from Yiddish (שמאָק, shmok), where it has similar pejorative meanings, but where its original and literal meaning is penis.
In the German language the word means "jewelry, adornment". The etymology of the pejorative meaning is a matter of some disagreement.
The lexicographer, Michael Wex, the author of How to Be a Mentsh (And Not a Shmuck), writes that the Yiddish term and the German term are completely unrelated. "Basically, the Yiddish word comes out of baby talk," according to Wex. "A little boy’s penis is a shtekl, a 'little stick'. Shtekl became shmeckle, in a kind of baby-rhyming thing, and shmeckle became shmuck. Shmeckle is prepubescent and not a dirty word, but shmuck, the non-diminutive, became obscene."
According to Leo Rosten in Hooray for Yiddish!, the pejorative use of the German "schmuck" derives from , which is closer to the original Yiddish word: and the transition of the word from meaning "jewel" to meaning "penis" is related to the description of a man's genitals as "the family jewels".
The Online Etymology Dictionary indicates that the term derives from Eastern Yiddish shmok, literally "penis", from Old Polish , "grass snake, dragon", but Rosten cites Dr. Shlomo Noble of the YIVO Institute for Jewish Research as saying that shmok derives from shmuck, and not the other way around.
Because of its generally being considered a vulgarity, the word is often euphemized as "schmoe", which was the source of Al Capp's cartoon strip creature the "shmoo". Other variants include "schmo" and "shmo".
Leo Rosten writes in The Joys of Yiddish that schmuck is commonly viewed among Jewish people as an obscene word that shouldn't be said lightly.Lenny Bruce, a Jewish stand-up comedian, wrote that the use of the word during his performances in 1962 led to his arrest on the West Coast, "by a Yiddish undercover agent who had been placed in the club several nights running to determine if [his] use of Yiddish terms was a cover for profanity".