The name Mac is a boy's name of Scottish, Irish origin meaning "son of". Mac and is often added to lists like Nicknames for Boys and discussed in our forums with posts like "CAF - Individual Namebanks IV".
From the experts:
In Ireland and Scotland, Mac and Mc mean "son of"; here, Mac is a generic fella, or a short form cooler than either Matt or Max. Mac can be a nickname of any longer Mac or Mc starting name such as McCoy or Macalister. If you want to make it feel more complete, you can always spell it Mack.