What was the name of the Egyptian letter?

Hieroglyphics or hieroglyphic writing. Also, such a definition as “hieratic writing” is applied. It is no longer a writing in hieroglyphs, but rather a drawing letter. The Egyptians combine the features of ideography (when a drawing does not even mean a word, but maybe a whole phrase or idea), phonetic writing (when a sign or drawing is tied to a clearly defined sound in advance) and syllabics (when a separate sign can denote a syllable). The self-name of the letter is Madu Netcher.