Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
Mac-, M’, Mc-
are forms of the Celtic word meaning “son,” the Mc and M’ forms being sorts of contractions, variant spellings. As parts of proper names (MacKay, Macbeth, McKenzie, M’Donald) they are capitalized; the second element of such names is not always capitalized. Most reference books alphabetize names beginning with Mac-, Mc-, and M’ as though they were all spelled Mac, which is convenient when you are unsure of the spelling of the name you seek.
