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.

Mem is believed to derive from the Egyptian hieroglyphic symbol for water,

which had been simplified by the Phoenicians and named after their word for "water", mem (), ultimately coming from Proto-Semitic *may-.

The letter is named mīm, and is written in several ways depending on its position in the word:

Some examples on its uses in Modern Standard Arabic:

Mīm is used in the creation of ism words (i.e. nouns and adjectives; they are treated fundamentally the same in Arabic grammar). Specifically, mīm is used in the creation of the masdar (verbal noun) of Stem III verbs (the masdar of verbs on the pattern fāʿala is mufāʿala), of subject and object nouns for verbs of Stems II-X (using the example of Stem II, subject nouns—called fāʿil words because of their form in Stem I—are mufaʿʿil for verbs of Stems II-X, and object nouns—called mafʿūl also because of their Stem I form—take the form mufaʿʿal for verbs of Stems II-X). Place-nouns are also created with mīm; the pattern mafʿal is used to create maktab "office" from the triliteral k-t-b (to write) and maṣnaʿ "factory" from ṣ-n-ʿ (to make).

Hebrew spelling: מֵם

Mem represents a bilabial nasal [m].