Lughnasadh is a traditional Gaelic holiday celebrated on 1 August. It originated as a harvest festival, corresponding to the Welsh Calan Awst and the English Lammas. In Old Irish (or Old Gaelic), the name was usually spelled Lugnasad. Later spellings include Luġnasa, Lughnasadh and Lughnasa.
In Modern Irish (Gaeilge), the spelling is Lúnasa, which is also the name for the month of August. The genitive case is also Lúnasa as in Mí Lúnasa (Month of August) and Lá Lúnasa (Day of Lúnasa). The word násadh means a feast, fair, assembly, or celebration, but is unstressed when used as a suffix on Lughnasadh.
In Modern Scottish Gaelic (Gàidhlig), the festival and the month are both called Lùnastal.
In Manx (Gaelg), the festival and the month are both called Luanistyn. The day itself may be called either Laa Luanistyn or Laa Luanys.
In Welsh (Cymraeg), the day is known as Calan Awst, originally a Latin term, the Calends of August in English.
Lughnasadh or Lammas is also the name used for one of the eight sabbats in the Wiccan Wheel of the Year. It is the first of the three autumn harvest festivals, the other two being the Autumn equinox (also called Mabon by Wiccans) and Samhain. It is seen as one of the two most auspicious times for handfasting, the other being at Beltane. Some Wiccans mark the holiday by baking a figure of the "corn god" in bread, and then symbolically sacrificing and eating it.
In Irish mythology, the Lughnasadh festival is said to have been begun by the god Lugh (modern spelling: Lú) as a funeral feast and sporting competition in commemoration of his foster-mother, Tailtiu, who died of exhaustion after clearing the plains of Ireland for agriculture. The first location of the Áenach Tailteann gathering was at Tailtin, between Navan and Kells. Historically, the Áenach Tailteann was a time for contests of strength and skill and a favored time for contracting marriages and winter lodgings. A peace was declared at the festival, and religious celebrations were held. The festival survived as the Taillten Fair, and was revived for a period in the 20th century as the Telltown Games .
A similar Lughnasadh festival was held at Carmun (the exact location of which is under dispute). Carmun is also believed to have been a goddess of the Celts, perhaps one with a similar tale as Tailtiu.
In Ireland, some people continue to celebrate the holiday with bonfires and dancing. The Catholic Church in Ireland has established the ritual of blessing fields on this day. In the Irish diaspora , survivals of the Lúnasa festivities are often seen by some families still choosing August as the traditional time for family reunions and parties, though due to modern work schedules these events have sometimes been moved to adjacent secular holidays, such as the Fourth of July in the United States.