How did Co Down in Ireland get its name?

The name "Co Down" does not refer to a county in Ireland. There are two counties in Northern Ireland that share similar names, County Down and County Londonderry. "Londonderry" is sometimes shortened to "Derry," but it is not referred to as "Co Derry."

Here is a brief explanation of the origins of the names of County Down and County Londonderry:

1. County Down:

The name "Down" is believed to be derived from the Irish word "dun," which means "fort" or "stronghold." The county's name is thought to refer to the numerous ancient hillforts found within its borders. Another possible origin is from the Gaelic word "dubh," meaning "black," in reference to the dark soils found in the area.

2. County Londonderry:

The name "Londonderry" comes from the Irish words "Doire Cholm Cille," which means "Oak Wood of Colum Cille." This name refers to the ancient monastery founded by Saint Columcille in the 6th century. Over time, the name evolved into "Derry" and eventually "Londonderry," likely influenced by the English colonization of the area in the 17th century.

So, Co Down is not a county in Ireland but likely refers to County Down or County Londonderry. Please clarify if you had a different location or question in mind.