[מ; final, ם].
The thirteenth letter of the Hebrew alphabet, also later used outside the Hebrew Scriptures, as a number to denote forty. It is one of the five Hebrew letters that have a different form when used as the final letter of a word. The name assigned to the letter means “water.”
Mem corresponds to our English “m,” which is derived from it through the Greek my. In the Hebrew, it appears as the initial letter in each of the eight verses in Psalm 119:97-104.