from The Century Dictionary.
- noun One who tolls a bell.
from the GNU version of the Collaborative International Dictionary of English.
- noun obsolete One who tolls a bell.
Sorry, no etymologies found.
Now, I'm no racism grassy knoller, but I think we know.
Though the connection with conspiracy theories appears to have begun with grassy-knoller (and, perhaps, mooner - the name for people who believe the moon landings were staged in Arizona), the derogatory force of - er has a long pedigree in common usage too, from mouth-breathers to knuckle-draggers.