The Collaborative International Dictionary
Grumblingly
Grumblingly \Grum"bling*ly\, adv. In a grumbling manner.
Wiktionary
grumblingly
adv. While or as if grumble
Usage examples of "grumblingly".
Grumblingly, Gomja batted away Teldin's hand and tried to roll over, setting the whole cart creaking with his shifting weight.