Em (Cyrillic) in the context of Bilabial nasal

Mu (/ˈm(j)uː/ ; uppercase Μ, lowercase μ; Ancient Greek μῦ [mŷː], Greek: μι or μυ—both [mi]) is the twelfth letter of the Greek alphabet, representing the voiced bilabial nasal IPA: [m]. In the system of Greek numerals it has a value of 40. Mu was derived from the Egyptian hieroglyphic symbol for water, which had been simplified by the Phoenicians and named after their word for water, to become 𐤌 (mem). Letters that derive from mu include the Roman M and the Cyrillic М, though the lowercase resembles a small Latin U (u).

Mem (also spelled Meem, Meme, or Mim) is the thirteenth letter of the Semitic abjads, including Hebrew mēm מ‎, Aramaic mem 𐡌, Syriac mīm ܡ, Arabic mīm م‎, and Phoenician mēm 𐤌. Its sound value is [m]. It is also related to the Ancient North Arabian 𐪃‎‎‎, South Arabian 𐩣, and Ge'ez መ. The Phoenician letter gave rise to the Greek mu (Μ), Etruscan , Latin M, and Cyrillic М.