This is the Gaelic term for a burial mound and in Ireland; it is commonly used to refer to Faeries.
You will often hear the term ‘daoine sidhe’ (pronounced deenee shee) meaning faerie folk mentioned in these parts. Many consider Sidhe to be the true Faerie folk and various explanations for this are given.
The legend of the Sidhe Faerie Folk in Ireland
In Ireland the Sidhe are considered to be ancient Celtic gods. Pagan spirits of Ireland were known as the Tuatha de Danann.
Tuatha de Danann means ‘Children of Danu or Dana’ a legendary race of people who overthrew the Irish in ancient times. When the Tuatha de Danann was overthrown themselves by the Milesians they took shelter in earth barrows (sidhe). Deprived of offerings and affection the Tuatha de Danann shrivelled and withered until they became the little people.
By day the Sidhe tend to their cattle that they sell or use to trade at fairs. Point of interest Pre-Christian Irish deities were involved in cattle trading. The Tuatha de Danann was once called Marcra Shee (faerie cavalcade) or Slooa-Shee (faerie host).
Some Irish Christians believe is that Faeries are fallen angels. Angels that were not bad enough to be dammed into Hell, but who were beyond saving and could not regain their place in Heaven. So they were left to live among us as Faeries here in the mortal realm.
There are those that believe that Faeries are none of the above and are spirits who live among us going about their lives like any one of us.