As many of you have noted, the Mc in your surname denotes "Son of" in the Gaelic language.None has commented yet that the Cathern in your name is Gaelic.In that language, "cat" means battle or war.Thus Catanach means war-man or warrior.Clan Chattan has nothing to do with kitty-cats.It was the great war-clan of medieval times.
The plural of catanach in olden times was Ceithereirne or Ceatharn, meaning "warriors." In his History of Rome, written 2,000 years ago, Livy described how a Celtic clan he called the Ceutrone attacked Hannibal's army and its elephants as they crossed the Alps in September 217 BC.Livy mistakenly believed they were a distinct clan.They were merely the warriors of the local clans who had been cheated by Hannibal's quartermasters.
Any good English dictionary has the word "cateran".To the invading and occupying English, the Scottish ceatharn were Highland bandits or Highland robbers and that is the "Anglish" meaning given both cateran and katrine. Loch Katrine, north of Glasgow, is literally Lake of the Warriors, but the English translate it as Lake of the Highland Bandits. It is the lake of Sir Walter Scott's Lady of the Lake.
In the Soundex system of surname indexing used in the LDS Library at Salt Lake City, Cathern is rendered KTRN by dropping vowels and H's.Catron, my surname, is also KTRN.Loch Katrine is pronounced exactly as my name, CAT-rin.The Irish dropped the "t" sound centuries ago, thus their version of our surname is Kern, which the English have translated as a woodsman, ruffian, country boy, or cowboy.
By medieval times, the best mercenaries of Europe were the Scottish Ceatharn and their name is found in every nation where they practiced their deadly trade centuries ago.There are Swiss, German, Dutch, French, Italian, and Spanish variants of the name.
So, now all you Sons of Warriors go out and quaff asingle malt in celebration of your heroic name and the ancestors who earned it.