ETYMOLOGY
from grumble (vb.), in imitation of Muggletonian and Grindletonian, names of religious sects in the 17th century
EXAMPLE
“…Whether great Sect of Grumbletonians in the Countrey, whom nothing will satisfie, been’t the worst Enemies which this Countrey can have?…”
From: Further Quaeries upon the Present State of New-English Affairs
By S.E., 1690
Lexicophilia 