The garment worn by the man in the picture is called a breacan feile or belted plaid. It is sometimes called a feilemor or great kilt. The modern kilt is derived from the breacan feile and is sometimes referred to as a feilebeag or small kilt in that it does not extend above the waist of the wearer. These garments are all made of wool woven in a tartan sett or patterns.
Underwear consisted of a shirt that reached to just above the knees.