Definition of opponent for English Language Learners. : 1  a person, team, group, etc., that is competing against another in a contest. : 2  a person, group, etc., that is against something (such as an action, law, or system) : someone or something that does not want something to exist, be done, etc.
On the Celtic calendar, the traditional first day of winter is 1 November (Samhain, the Celtic origin of Halloween); spring starts 1 February (Imbolc, the Celtic origin of Groundhog Day); summer begins 1 May (Beltane, the Celtic origin of May Day); the first day of autumn is 1 August (Celtic Lughnasadh).
A crowd celebrates last year's winter solstice at Stonehenge. Photograph by Matt Cardy, Getty Images Today is the winter solstice and the first day of winter in the Northern Hemisphere. It's all due to Earth's tilt, which ensures that the shortest day of every year falls around December 21. Some predicted that today would also mark Earth's doomsday, thanks to a longstanding rumor that the Maya calendar ends on December 21, 2012.