Definitions of mumble  [ˈmʌm bəl]  

2. [MIT] Expression of not-quite-articulated agreement, often used as an informal vote of consensus in a meeting: “So, shall we dike out the COBOL emulation?” “Mumble!”

3. Sometimes used as an expression of disagreement (distinguished from sense 2 by tone of voice and other cues). “I think we should buy a VAX.” “Mumble!” Common variant: mumble frotz (see frotz; interestingly, one does not say ‘mumble frobnitz’ even though ‘frotz’ is short for ‘frobnitz’).

4. Yet another metasyntactic variable, like foo.

5. When used as a question (“Mumble?”) means “I didn't understand you”.

6. Sometimes used in ‘public’ contexts on-line as a placefiller for things one is barred from giving details about. For example, a poster with pre-released hardware in his machine might say “Yup, my machine now has an extra 16M of memory, thanks to the card I'm testing for Mumbleco.”

7. A conversational wild card used to designate something one doesn't want to bother spelling out, but which can be glarked from context. Compare blurgle.

8. [XEROX PARC] A colloquialism used to suggest that further discussion would be fruitless.