"speechless, silent," from Yiddish, from German stumm "silent, mute" (see stammer (v.)).
Entries linking to shtoom
stammer v.
Old English stamerian "to stammer," from Proto-Germanic *stamro- (source also of Old Norse stammr "stammering," Old Saxon stamaron, Gothic stamms "stammering," Middle Dutch and Dutch stameren, Old High German stammalon, German stammeln "to stammer," a frequentative verb related to adjective forms such as Old Frisian and German stumm "mute"). Related: Stammered; stammerer; stammering; stammeringly.