The phrase âkeep mumâ is up there with the phrase ânix itâ in the âIâd like to know where that came fromâ sweepstakes for me.
The word âmumâ is an alteration of momme, which was used between 1350 and 1400 in Middle English with very close to the same meaning, âbe silent; do not revealâ⌠(According to the CIA/Wiki page)- Could be from The word âstummâ in the German language that also means to be âsilentâ.
Iâve just been lazy with this: mum | Search Online Etymology Dictionary
I can see the word ânixâ coming from the German ânichtsâ, or the verb âvernichtenâ - âto turn into nothingâ. Not convinced by the Stumm/mum thing, though - although the âmâ sound might originate in the same idea of muteness. Linguistically, I wouldnât think a phoneme like âstâ is likely to disappear without notice like thatâŚ