You searched for: “acrophony
acrophony (s) (noun), acrophonies (pl)
1. The sound of the initial or beginning of what was originally a picture-symbol or hieroglyph of an object to represent phonetically the initial syllable or sound of the name of the object; e.g. employing the symbol of an ox, aleph, to represent the syllable or letter.
2. The naming of a letter by a word whose initial sound is the same as that which the letter represents.