DuckCorp Dico

Found one definition

1.                 From en.wiktionary.org:
                   
   
   
                   
                     
   [grumbles]
   
   ** English
   
   *** Etymology
   Apparently, a variant of [en].
   
   *** Proper noun
   [es]
   
    1. [en] .
   **** Statistics
   
    - According to the 2010 United States Census, _Grumbles_  is the 35345 <sup> th </sup>  most common surname in the United States, belonging to 637 individuals. _Grumbles_  is most common among White (92.31%) individuals.
   *** Further reading
   
    - [R:en:DAFN]