M, m [Called ‘em’]. The 13th LETTER of the Roman ALPHABET as used for English. It originated in the Phoenician symbol mem, a zigzag line probably representing water (the word for which began with that letter: compare HEBREW mayim water). It was adapted by the Greeks as mu (M) and adopted with the same sound value by the Etruscans and the Romans.

Sound value

The sound represented by m is normally a voiced bilabial nasal, but before /f/ the closure may be labio-dental rather than bilabial (comfort), and before /b, p/ an n may be pronounced /m/: none better (‘numbetter’), input (‘imput’). Assimilation of this kind helped turn the late MIDDLE ENGLISH phrase in kenebowe (‘in keen bow’, that is, in a sharp curve) into present-day akimbo.

Double M

(1) Final m is normally single in monosyllabic words: am, aim, tame, rim, time, home, some, room, gum, fume, rhyme. A suffix beginning with a vowel prompts mm after a short vowel (jammed, brimming, drummer), unless a silent consonant or final e in the base word intervenes (thumbed, coming, damning: contrast damming). (2) Medial mm normally signifies a preceding short vowel (contrast comma/coma), and also occurs in assimilations of Latin prefixes ending in n: immaterial (not *inmaterial). Similarly, Greek syn- produces mm in symmetry. (3) M-doubling is inconsistent after short vowels, as shown by the pairs camel/mammal, image/scrimmage, lemon/lemming, prompting such common consequent misspellings as *accomodate, *ommit.

Syllabic M

The letter m can function syllabically, as in rhythm, chasm.

Silent M

The m is silent in initial Greek-derived mn- (mnemonic, Mnemosyne), but is pronounced after a prefix (amnesia). See B.