Definify.com

Webster 1913 Edition

Adj.

Low; indistinct; inarticulate.

–

Mum′bling-ly

adv.

The miserable

Mumbo Jumbo

they paraded.

Dickens.

An object of superstitious homage and fear.

Carlyle.

ppr.

Uttering with a low inarticulate voice; chewing softly or with a grumbling sound.

mumbling

mumbling ‎(plural mumblings)

An act in which someone mumbles something
- 2008 March 20, “Obama Challenges the Racial Divide”, in New York Times:
  The second is the contrast with the inarticulate stumblings, mumblings, evasions and half-truths of our current president.