Randy Lee Eichoff is a professor at UTEP. He is very open and friendly and has told me that his PhD is in Old Celtic. He recently published a tranlation of Cooley's Cattle Raid, the oldest literature in Western European history. He says in the celtic languages, "cat or Cath" means war or battle. A catanach (a Scottish surname today) means war-fellow or warrior. The plural was catron or caitheine or, in Irish Gaelic, kern. The modern English word is cateran. Look it up in a good dictionary. To the english, the name means Highland bandit, raider, marauder, etc. McCatheren and McHatton are variants with the "son of" Mc added. There is a Scottish clan organization called Clan Chattan. Randy says the "h" is silent, so it is pronounced Catan. They were small families (clans in Scots Gaelic) who united in times of war, thus, Clan Chattan is "War Clan".
If you study Irish and Scottish history, the excellent mercenaries they have produced for centuries are called the Wild Geese. The Gaelic word for a wild goose is catan. Get it?