Mac Amhalghaidh variant forms of the name. A modern variant is Mac Amhalaí. Another is Mac Amhalaidh. Another variant is Mac Amhalghadha. Variant forms of "Mac Amhalghaidh" and "Mac Amhalghadha" include Mag Amhalghaidh and Mag Amhalghadha. "Mac Amhalghaidh" translates into English as "son of "Amhalghaidh"", or "son of "Amhalghadh"". The surname originated as a patronym, however it no longer refers to the actual name of the bearer's father. The personal name "Amhalghaidh", also spelt "Amhalghadh", is an old Gaelic name, and is of uncertain origin and meaning. "Mac Amhalghaidh" is a masculine surname. The form of this surname for unmarried females is
Mac and Mc together example has been taken as representative of a possible paradigm. A book on filing rules from 1918 gives an example showing Mc and M' treated as abbreviations, i.e. for Mac, and ordered as if in the expanded version; and a similar book from 1922 makes the rule one of a number that apply also to St. (Saint) and Mrs. (Mistress). A 1938 book that is a comparative study of cataloguing in various British libraries regarded Mac + Mc + M' sorting as an example of achieved "standardisation" in alphabetisation. It gave further examples where, it argued, such standardisation would be