Old English Ymbrendaeg, Ymbren, 12 days of the year (divided into four seasonal periods, hence Medieval Latin name quatuor tempora) set aside by the Church for fasting and prayers, from Old English ymbren "recurring," corruption of ymbryne "a circuit, revolution, course, anniversary," literally "a running around," from ymb "round" (cognate with Greek amphi, Latin ambo; see ambi-) + ryne "course, running" (see run, n.). Perhaps influenced by a corruption of the Latin name (compare German quatember, Danish tamper-dage). The Wednesday, Friday, and Saturday after the first Sunday in Lent, Whit-Sunday, Sept. 14, and Dec. 13, set aside for prayer and fasting.