The noun ηχος (echos) means sound or rather a relay by means of sound (hence our English word echo). It refers mostly to the sound of spoken words (or trumpets): rumors that ripple radially though society, are "heard" and verified or weighed and possibly amended, and then sent ever onward. Our word speaks of sound the way a so-called smart-swarm processes data: audible information passed by word of mouth, from and to all directions. Sound in the sense of physically vibrating air is mostly expressed by the noun φονη (phone). Our noun evolved from the older ηχη (eche), which also described a murmuring, voice-like sound, and particularly a sound that carries a whisper like a rumor to-and-fro along a circuit.

The origin of these words isn't overly clear but they possibly stem the same Proto-Indo-European root that also gave Latin the verb vagio, to cry like a young child (hence the ever useful English adjective vagient, meaning crying like a child). Echo (Ηχω, Echo) was also the name of an unfortunate mountain nymph, who was cursed by Hera to only be able to utter words she just heard, which means that she couldn't express her love to Narcissus, since he only flattered himself. When he died, she died, and only her disembodied voice remains, still repeating whatever she last heard. Sadder still, the pseudo-homophone of Echo's name, namely the verb εχω (echo), means to have or hold.

Our noun ηχος (echos), acoustic relay, sound or resound (i.e. grapevine fame) occurs in Luke 4:37, Acts 2:2 and Hebrews 12:19 only. From it derive: