Ɱ
The letter Ɱ (minuscule: ɱ), called M with hook (in some literature referred to as Left-tail M; sometimes informally referred to as meng or emg, analogous to eng ⟨ŋ⟩) is a letter based on the letter M. Its minuscule ⟨ɱ⟩ is used to transcribe a voiced labiodental nasal in the International Phonetic Alphabet.
In Americanist tradition, the lowercase ⟨ɱ⟩ has occasionally been used for transcribing a voiced labiodental nasal, as in the IPA, and the uppercase ⟨Ɱ⟩ for a voiceless labiodental nasal.