The word Cnidaria is spoken without the initial "C", and with a long "i". So it sounds like "Naidaria". In a similar way, the term Ctenophore is pronounced as "Teenophore". Originally, a Greek kappa was in front of the words, and it was pronounced. The name comes from Greek language "knidi", "nettle", thus mening "nettle-like animals" as all cnidarians have stinging cells like nettles.