What is the original meaning of the word "plaid"?

“Plaid” comes from the Scots Gaelic word “plaide,” which means “blanket.” The Celts were among the first people in Europe to weave and dye in multiple colours, creating bright, festive clothing which was often a source of commentary when people from other regions of Europe visited. Celtic men and women both wore heavy wool plaids draped across their bodies to protect themselves from harsh and damp weather.

Over time, the plaid came to be associated specifically with Scotland, a bastion of Celtic culture. Since the 16th century it has meant a type of twilled woollen cloth, often with a tartan or chequered pattern. It is worn by both sexes for warmth and for protection against the weather. It is a special dress of the Highlanders, and forms part of the uniform of certain infantry regiments in the British army.