M, m, the twelfth letter of the Latin alphabet (J not being distinguished from I in the class. period), corresponds in form and sound to the Greek M; the Latin language, however, does not combine an initial
m with n , as in the Greek μνᾶ, μνῆμα, μνίον, μνόος, etc.; hence, the Greek μνᾶ became Latin mĭna. The Latin language, unlike the Greek, tolerated a final m; but its sound was obscure, Prisc. p. 555 P. (cf. Quint. 12, 10, 31), and before an initial vowel, even in prose, was scarcely heard (hence Verrius Flaccus proposed to represent it by an M half obliterated, thus, N). In poetry, the vowel also immediately preceding the m was elided, Quint. 9, 4, 40; 11, 3, 34; 109; Diom. p. 488 P.; Prisc. p. 555 sq. ib.; Val. Prob. 1392; 1440 ib. To this rejection of the m at the end of words before vowels are owing the forms attinge, dice, ostende, facie, recipie, for attingam, dicam, ostendam, faciam, recipiam; v. the letter E; and the forms donec for donicum, coëo, coërceo for com-eo, com-erceo; circueo, circuitus, for circum-eo, circum-itus; veneo for venum eo; vendo for venum do; animadverto for animum adverto, etc.— M is substituted for p or b before a nasal suffix, as som-nus, cf. sopor, sopio; scamnum, cf. scabellum; Samnium for Sabinium; summus, cf. sub, super. Often also for n before a labial, as impello for inpello; cf. rumpo, root rup-; lambo, root lab-, with fundo, root fud-, etc.— M corresponds with the m of all Indo-European tongues, like Gr. μ; cf. simul, ἅμα; me, με; mel, μέλι; magnus, μέγας; but in inflections final m corresponds with Gr. ν, as navem, ναῦν; musarum, μουσῶν; sim, εἴην, etc.— M is interchanged most freq. with n; so eundem, eandem, quendam, quorundam, tantundem, from eum, eam, quem, quorum, tantum; and, on the other hand, im is written for in before labials and m : imbellis, imbibo, imbuo; impar, impedio, imprimo, immanis, immergo, immuto, etc. Thus also m regularly stands for the final ν of neuters borrowed from the Greek. A collat. form of Nilus, Melo, for Νεῖλος, is mentioned in Paul. ex Fest. p. 7; 18 and 129 Müll.—The Latin m also interchanges with Gr. β: mel-ior, βελ-τίων; mortuus (Sanscr. mrita), βροτός (v. for full details, Corss. Ausspr. 1, pp. 263 sqq.).As an abbreviation, M. denotes most freq. the praenomen Marcus, and less freq. magister, monumentum, municipium; v. the Index Notar. in Inscr. Orell. 2, p. 464 sq. M' denotes the praenomen Manius. As a numeral, M, standing for CIC, denotes the number 1000.