A Ghillie shirt, also known as Jacobean or Jacobite, is an informal traditional shirt usually worn with a kilt

Kilt

The kilt is a knee-length garment with pleats at the rear, originating in the traditional dress of men and boys in the Scottish Highlands of the 16th century. Since the 19th century it has become associated with the wider culture of Scotland in general, or with Celtic heritage even more broadly...

. The term Ghillie refers to the criss-crossed lacing style as also seen on the Ghillie Brogue. Ghillie shirts are considered to be more casual than their shirt and waist-coat counterpart that is normally seen with the kilt. The Ghillie shirt existed before the kilt, with there being no documentation for kilts until 1575.

Ghillie shirts are traditionally used for dances or ceilidh

Céilidh

In modern usage, a céilidh or ceilidh is a traditional Gaelic social gathering, which usually involves playing Gaelic folk music and dancing. It originated in Ireland, but is now common throughout the Irish and Scottish diasporas...

s as they are light and spacious to allow for air to pass through. They do not need to be worn with any sort of tie. The Irish version of the Ghillie shirt is the Grandfather shirt

Grandfather shirt

For the Scottish version of a Grandfather shirt see Ghillie shirtA Grandfather shirt or Granddad shirt, is a long sleeve flannel or brushed cotton collarless shirt worn throughout Ireland. Traditional shirts are white with coloured vertical stripes. Longer shirts are used as nightshirts or...

.