The earliest examples of nun depict a snake. Typically it looked like the Egyptian sign for a resting cobra which in Egyptian was used for the sound usually transcribed as “dj” by scholars and which was probably pronounced similar to the way Ethiopian Jews pronounce the tsadi. Other variations of early nun looked more like the Egyptian sign for a type of viper with pointy eyebrow ridges which was used in Egyptian for the f sound. (People unfamiliar with this snake wrongly assume that the sign depicts a slug.) However in Hebrew nun is used for the n sound.

But why is it called nun? “Nun” does not mean a snake its an old word for a fish! Of course there is a Hebrew word for snake beginning with the n sound – nachash – surely the letter should be have been called nachash not nun? In fact in the Ethiopic alphabet which descends from an early splitting away from the Hebrew alphabet, the corresponding letter is called nahas, the Ethiopic equivalent of Hebrew nachash! This strongly suggests that originally the letter was indeed called nachash. So why did the name become nun? Some have suggested that perhaps an eel is intended as an eel is a fish that looks like a snake, but there is no evidence of the word “nun” meaning specifically eel in any Semitic language. A more straightforward explanation is that, lets face it, people don’t like snakes! Once the letter shape had evolved and no longer clearly resembled a snake, the name would have been changed to nun, similar in structure to the name mem and with a less creepy meaning!

Why is nun listed after mem? With mem we started the series of nasal humming sounds. Mem was the humming sound at the lips. The next highest articulation position is the back of the tongue and soft palate – this the position of the English ng sound, but that sound didn’t exist in the dialect of Hebrew that the alphabet order was based on. The next highest position is the tip of the tongue and upper teeth – this gives us the n sound and so nun comes after mem.