Mim is the twenty-fourth letter of the modern Arabic order and the thirteenth of the older abjad order, from which it takes the numeral value forty. It is written as a small closed loop with a tail that falls below the line, and it joins on both sides, keeping the loop and dropping the tail when it does. In the middle of a word it is little more than a filled circle sitting on the line, which makes it one of the most recognisable letters in a dense hand.
Mim is a moon letter, so the lam of the definite article is pronounced before it. Its sound is the bilabial nasal, the m of English, and it is one of the few Arabic consonants that a speaker of a European language can produce without instruction.
Its name descends from the Northwest Semitic mem, the cognate of Hebrew mem and Syriac mim, whose sense was water, and it holds the numeral value forty that Hebrew mem holds. In the Hebrew tradition mem is one of the three mother letters of the Sefer Yetzirah and carries the element water in that system; Arabic has no corresponding classification of its own letters, and the atlas does not transfer one across.
Mim is among the most frequently occurring letters in the disjoined groups that open certain suras. It stands beside the pharyngeal ha in a large group of them and beside alif and lam in others, and it is one of the letters that has attracted most comment in the arguments about what those groups mean.