Dr. Plummer mentions that "Ἐγόγγυζον" (which can mean "grumbled" or "murmured," among other things) is "an onomatopoetic word."
I don't have any particularly significant comment about this; I just found it interesting that in the three foreign language translations that I follow along in, this onomatopoetic quality is retained.
German: "Da murrten die Juden über ihn, weil er sagte: Ich bin das Brot, das vom Himmel gekommen ist,"
French: "Les Juifs murmuraient à son sujet, parce qu'il avait dit: Je suis le pain qui est descendu du ciel."
Latin: "Murmurabant ergo Iudaei de illo quia dixisset ego sum panis qui de caelo descendi"
The French murmure and the Latin murmurare both mean "to murmur," but the German murren means "to complain about."
