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).
In Canada and the rest of the northern hemisphere, the first day of the winter season is the day of the year when the Sun is farthest south (on December 21 st or 22 nd).