Mc

Mc is a surname prefix derived from the Gaelic mac, meaning "son of." It is used primarily in Scottish and Irish names and is a contracted form of the longer Mac spelling. The prefix signals patronymic origin, indicating descent from an ancestor whose name followed the prefix.

In practice, Mc functions as a variant spelling of Mac. Both forms appear in similar surname groups (for example, McDonald, McGregor, McLean, McCarthy, McMahon), and the choice between Mc and Mac often reflects family tradition, regional practice, or anglicization over time. In some older or less common traditions, a form like M’ appears before vowels, though this is rare today. Surnames starting with Mc have spread widely with the Scottish and Irish diasporas, and are now common in North America, Australia, and other English-speaking regions.

The use of Mc as a prefix is primarily genealogical and onomastic, helping trace family lineage and regional origins. For researchers, distinguishing Mc from the full Mac form can aid in locating historical records, immigration documents, and birth or marriage registries. Mc is one of several prefixes used in Gaelic naming systems that reflect kinship and descent, alongside Mac and other orthographic variants.

Beyond names, the uppercase abbreviation MC (or MC) is widely used in other contexts, such as Master of Ceremonies or in business and media acronyms. These uses are unrelated to the Gaelic naming prefix Mc.