Beltane or Beltaine is the anglicised spelling of Old Irish Beltain the Gaelic name for either the month of May or the festival that takes place on first day of May.

Beltane is the anglicised spelling of Old Irish Beltain the Gaelic name for either the month of May or the festival that takes place on first day of May.

Beltane was historically a Gaelic festival celebrated in Ireland, Scotland and the Isle of Man. Bealtaine and Samhain were the leading terminal dates of the civil year in medieval Ireland, though the latter festival was the more important. The festival regained popularity during the Celtic Revival and remains observed in the Celtic Nations and the Irish diaspora.

The feast was also known as Céad Shamhain or Cétshamhainin from which the word Céitean derives. Beltane was formerly spelled 'Bealtuinn' in Scottish Gaelic; in Manx it is spelt 'Boaltinn' or 'Boaldyn'. In Modern Irish, Oidhche Bealtaine or Oíche Bealtaine is May Eve, and Lá Bealtaine is May Day. Mí na Bealtaine, or simply Bealtaine is the name of the month of May.
In Neopaganism, Bealtaine is considered a cross-quarter day, marking the midpoint in the Sun's progress between the spring equinox and summer solstice. The astronomical date for this midpoint is closer to 5 May or 7 May, but this can vary from year to year.