Green week (Зелёные Святки, also known as Семи́к – Semik, ukrainian: Зелені Свята) is an ancient Slavic fertility festival celebrated in early June and closely linked with the cult of the dead and the spring agricultural rites. It usually fell upon the Thursday of the Green Week (better known as Trinity Week in Russia and the Whitsuntide week in Britain). Its name is derived from the Slavic word for "seven", because the Green Week was the seventh (sometimes the eighth) week after Easter.