Derived from patronomycs - Mac or Mc means son (of), similar in use to the Irish O which originally meant grandson (of) and Mac was also used in Ireland but largely died out leaving Mac/Mc surnames generally Scottish and O' surnames generally Irish. The MAc/Mc names are generally Highland surnames but not always so, Lowlander and Norse descendants also used this titling to some extent. Nic means daughter but the usage has not fed into surnames in the same way as Mac/Mc.

Mac is still used in Ireland and has not died out. So Mac is not generally Scottish an example is McNamara and McNamee. It is still a common prefix in Irish names.