its not my word, Bob, its a real word here is Oz (unless its one of our old family sayings thats stayed with me) I just checked my shorter macquarie dictionary and its not there - but you're most welcome to it!

in the absence of an authoritative definition i hereby offer:

grumblebum: boring old fart, cranky pants, miserable whinger...
sourpuss, miseryguts..

enjoy!

freda