Aos Sí

Aos sí (pronounced [iːsˠ ˈʃiː]; English approximation: /iːs ˈʃiː/ eess SHEE; older form: aes sídhe [eːsˠ ˈʃiːə]) is the Irish name for a supernatural race in Gaelic folklore, similar to elves. They are said to descend from the Tuatha Dé Danann or the gods of Irish mythology.
The name aos sí means "folk of the sí"; these are the burial mounds in which they are said to dwell, which are seen as portals to an Otherworld. Such abodes are referred to in English as 'shee', 'fairy mounds', 'elf mounds' or 'hollow hills'. The aos sí interact with humans and the human world. They are variously said to be the ancestors, the spirits of nature, or goddesses and gods.
In modern Irish, they are also called daoine sí; in Scottish Gaelic daoine sìth ('folk of the fairy mounds').
In the Irish language, aos sí, earlier aes sídhe, means "folk of the fairy mounds". In Old Irish, it was áes síde. The word sí or sídh in Irish means a fairy mound or ancient burial mound, which were seen as portals to an Otherworld. It is derived from proto-Celtic *sīdos ('abode'), and is related to the English words 'seat' and 'settle'.
David Fitzgerald conjectured that the word sídh was synonymous with "immortal" and is compared with words such as sídsat ("they wait/remain"), síthbeo ("lasting"), sídhbuan ("perpetual"), and sídhbe ("long life"). In most of the tales concerning the sí, a great age or long life is implied.
In medieval Irish literature, the names aes síde and fír síde (folk of the síd) are equivalent to the terms Tuath Dé and Tuatha Dé Danann. The only difference is that Tuath Dé tends to be used in contexts of legendary history and mythology.
Writing in the 7th century, the Irish bishop Tírechán described the sídh folk as "earthly gods" (Latin: dei terreni). The 8th century Fiacc's Hymn says that the Irish adored the sídh folk before the coming of Saint Patrick.
Due to the oral nature of Irish folklore, the exact origins of the fairies are not well defined. There are enough stories to support two possible origins. The fairies could either be fallen angels or the descendants of the Tuatha Dé Danann; in the latter case, this is equivalent with aos sí. In the former case, it is said that the fairies are angels who have fallen from heaven, but whose sins were not great enough to warrant hell.
In many Gaelic tales, the aos sí are later literary versions of the Tuatha Dé Danann ("People of the Goddess Danu")—the deities and deified ancestors of Irish mythology. Some sources describe them as the survivors of the Tuatha Dé Danann who retreated into the Otherworld when fleeing the mortal Sons of Míl Espáine who, like many other early invaders of Ireland, came from Iberia. As part of the terms of their surrender to the Milesians, the Tuatha Dé Danann agreed to retreat and dwell underground.
In folk belief and practice, the aos sí are often appeased with offerings and care is taken to avoid angering or insulting them. Often, they are not named directly, but rather spoken of as "The Good Neighbours", "The Fair Folk", or simply "The Folk". The most common names for them, aos sí, aes sídhe, daoine sídhe (singular duine sídhe) and daoine sìth mean, literally, "people of the mounds" (referring to the sídhe). The aos sí are generally described as stunningly beautiful, though they can also be terrible and hideous.
Aos sí are seen as fierce guardians of their abodes—whether a fairy hill, a fairy ring, a special tree (often a hawthorn) or a particular loch or wood. It is believed that infringing on these spaces will cause the aos sí to retaliate in an effort to remove the people or objects that invaded their homes. Many of these tales contribute to the changeling myth in west European folklore, with the aos sí kidnapping trespassers or replacing their children with changelings as a punishment for transgressing. The aos sí are often connected to certain times of year and hours; as the Gaelic Otherworld is believed to come closer to the mortal world at the times of dusk and dawn, the aos sí correspondingly become easier to encounter. Some festivals such as Samhain, Bealtaine and Midsummer are also associated with the aos sí.
A sídh (anglicized 'shee') is burial mound (tumuli) associated with the aos sí. In modern Irish, the word is sí (plural síthe); in Scottish Gaelic it is sìth (plural sìthean); in Old Irish it is síd (plural síde). These sídhe are referred to in English as 'fairy mounds', 'elf mounds' or 'hollow hills'.
In some later English-language texts, the word sídhe is incorrectly used both for the mounds and the people of the mounds. For example, W. B. Yeats, writing in 1908, referred to the aos sí simply as "the sídhe". However, sidh in older texts refers specifically to "the palaces, courts, halls or residences" of the otherworldly beings that supposedly inhabit them.
The Aos sí are known by many names in Ireland, among them:
The banshee or bean sídhe (from Old Irish: ban síde), which means "woman of the sídhe", has come to indicate any supernatural woman of Ireland who announces a coming death by wailing and keening. Her counterpart in Scottish mythology is the bean sìth (sometimes spelled bean-sìdh). Other varieties of aos sí and daoine sìth include the Scottish bean-nighe (the washerwoman who is seen washing the bloody clothing or armour of the person who is doomed to die), the leanan sídhe (the "fairy lover"), the cat-sìth (a fairy cat), and the cù-sìth (a fairy dog).
The sluagh sídhe—"the fairy host"—is sometimes depicted in Irish and Scottish lore as a crowd of airborne spirits, perhaps the cursed, evil or restless dead. The siabhra (anglicised as "sheevra"), may be a type of these lesser spirits, prone to evil and mischief. However, an Ulster folk song also uses "sheevra" simply to mean "spirit" or "fairy".
Creideamh Sí is Irish for the "Fairy Faith", a term for the collection of beliefs and practices observed by those who wish to keep good relationships with the aos sí and avoid angering them. General belief in the Celtic otherworld, the existence of aos sí and the ability of the aos sí to influence the local area and its people are all beliefs characteristic of the Creideamh Sí. It is characterised as an aspect of Irish popular religion and exists syncretically with folk Christianity.
Effort is made by those who believe to appease local aos sí through food and drink. The custom of offering milk and traditional foods—such as baked goods, apples or berries—to the aos sí has survived through the Christian era into the present day in parts of Ireland, Scotland and the diaspora. Those who maintain some degree of belief in the aos sí also are careful to leave their sacred places alone and protect them from damage through road or housing construction.