Nancy Friedman recently alerted me to an American use of a Britishism I had been unfamiliar with. (As she does.) It was from a blog post by an American writer named Tim Carmody, referring to an interview with public radio figure Ira Glass, in which Carmody thought Glass was unforthcoming: “he kind of schtums up and falls back on generalities and a few broad compliments.”
The OED doesn’t have an entry for “schtum,” but, unsurprisingly, Green’s Dictionary of Slang does. Green’s says its origin was the Yiddish word for “silent” and gives these citations:
One immediately notices the array of spellings — shtoom, stumm, schtum, stumm, and stumpf — and the procession of Union Jacks, indicating all of the sources are British. In an admittedly less than comprehensive search, I was unable to find any other American uses beyond Carmody’s, other than an National Public Radio interview with the British author of a novel called Shtum (about a 10-year-old boy with autism who has never spoken). Therefore I’m classifying it as “Outlier.” (BTW, Green’s has a separate entry for the verb form Carmody used, “shtoom up.”)
The word apparently emerged from Yiddish to the British criminal underground; Green’s first citation is from a memoir of petty crime and prison by Frank Norman. I was able to antedate that by one year. British journalist Laurence Wilkinson’s 1957 book Behind the Face of Crime has this passage (the snippet view was all I could get from Google Books):
notoneoffbritishisms.com 
If you’ve ever seen n episode of Porridge, the 1970s-80s comedy starring the late, great Ronnie Barker as Norman Stanley Fletcher, an inmate of HMP Slade (a prison), the you would have heard this all the time. On sighting a prison officer, someone will mutter “shtum!” and everyone shuts up or starts pretending to talk about something else.
…in which Carmody thought Glass was unforthcoming: “he kind of schtums up and falls back on generalities and a few broad compliments.”
I don’t think Carmody quite gets shtum, as your other commentator says it does mean quiet. In conversation it usually has ‘keep’ in front of it.
Completely agree. I’ve only seen it used as an adjective. Using it as a verb is clearly an Americanism.
That was my impression as well, but then I saw Green’s Dictionary of Slang had these British citations (admittedly three from the same author): 1958 [UK] F. Norman Bang To Rights 72: You can always shtoom up if any screws are earholeing.
1962 [UK] F. Norman Guntz 90: This confused Fred so he shtoomed up.
1979 [UK] F. Norman Too Many Crooks Spoil the Caper 138: She got the message and shtoomed up.
2001 [UK] N. Barlay Hooky Gear 119: I’m waitin for him, kind of stumm up by his words like he slap me too.
This (non-Jewish) New Yorker knows “shtum” as a Yiddishism, not as a Britishism, or British Yiddishism.
Totally NY & Chicago Yiddish from way back when whole neighborhoods spoke Yiddish and were acquiring English. Always wondered how it made it into more mainstream Brit Engl. Maybe coming back to US via that route, but it never really left, so far as I’m concerned.
I get the impression that many Yiddish words made it into British English directly from the thriving Jewish neighbourhood in the East End of London. Jewish characters in sitcoms and the like were always using Yiddish terms and they made their way into mainstream British English that way.
The word “schmutter” meaning clothing turned up in a crossword I was doing recently and I’m sure I heard that word on radio and television long ago. (I don’t remember much about it, but there was a popular sitcom in the sixties called Never Mind the Quality, Feel the Width, about a Jewish and an Irish tailor working together. I’m sure schmutter would have been used on that.)
I’d never heard of “schtoomed up”; the familiar term for me is to “keep schtum.
The phrase “keep shtum” is reasonably common but I don’t think I’ve ever heard the word ‘in the wild’ outside of this phrase. Possibly a fossil word in BrE?
“One immediately notices the array of spellings — shtoom, stumm, schtum, stumm, and stumpf — and the procession of Union Jacks, indicating all of the sources are British.”
It has a variety of spellings because Yiddish is written in modified Hebrew letters. Thus any word from Yiddish is transliterated. There is now a standard for this — YIVO Yiddish — but it’s fairly new.
I think, RobJFH, that the imperative “Shtum” as in Catherine Rose’s post is common enough in BrE
By the way, the OED does have an entry for shtoom (Also schtoom, shtum(m), etc.): https://www.oed.com/view/Entry/178981.
I may have missed it in the comments, as I’m just catching up now, but here to suggest that the Yiddish comes form the German “Stimme,” or “voice,” which is pronounced with an “sh” sound. Colloquially, Stimme takes the meaning of vote, as in “Meine Stimme hast du,” (You have my vote). Also used as a verb to mean “tune,” as in tune an instrument, or to indicate agreement “Das stimmt,” meaning “That’s true” in the sense that it rings true or resonates.
I should have made clearer that “stumm” (meaning mute or speechless) is related to Stimme, distinguished from the silence suggested by “Stille” (as in Stille Nacht) or Ruhe (peace).
Excellent. I found your comments through researching my own personal quest regarding the relationship of Stimme and Stumme. The potential of a simple vowel change causing meaning to go from „voice“ to „voiceless“.
I also loved your explanation of tune, resonate, agreement.
However, I did not get the allusion to Stille (I) and Ruhe (U). I am a beginning self-learner of the German language. Thanks.
Shin
Tet
Vav
Mem
Ayin
Nun (final)
shtumen – be quiet, be silent
Shin
Tet
Yod
Mem
Ayin
Nun (final)
shtimen – vote, voice, tune, align, agree
שטומען
שטימען
στόμα – mouth (Greek)
Possible as you made allusion, I versus U in Hebrew pronunciation would make Stimme – open mouth, voice, vote.
Whereas Stumme with U would mean closed mouth, be quiet, be silent, shut up?
At least that is how I am going to remember these two German words with a root in Greek and Hebrew.
Not Hochdeutsch or modern standard German. It’s Yiddish which is a dialect of Middle High German spoken by Jews in Central and Eastern Europe before WWII.
In England Jews first settled in the East End. Cockneys who lived there rubbed shoulders, did business (not all lawful) with them, and picked up some vocabulary.
The inconsistency in spelling is due to two factors.
Yiddish is written in letters of the Hebrew Aleph-Bet. The schemes for transliterating written Yiddish into English-Latin letters are consistent with English pronunciation but not with Modern Standard German spelling conventions. E.g. the German word sein is the root of the verbs of being. The transliteration of that word from Yiddish into English-Latin letters is zeyn, which is pronounced the same as sein. One might suspect that politics not linguistics drove the transliteration scheme.
Second Cockney is not generally a written dialect. People wrote what they heard.
American here. I used to know a profane pipefitter foreman who would refer to a person as “stumf**ked”, meaning that they were so stupid that they couldn’t articulate a coherent thought, to the point of being silent. Given his last name, perhaps he learned the term from an older eastern European relative.