Many people will know that Oxford has three terms (Michaelmas; Hilary; Trinity); each of them contains eight weeks of "Full Term", in which undergraduates are expected to be resident. Each week is a Sunday-Saturday week, and is known as First week ... etc.. Increasingly, Colleges expect undergraduates to come back before First Week so as to get geared up and write Collection Papers to prove that they did their Vacation reading; and this week has come to be called Noughth Week (I apologise to mathematicians). Technically, the terms are rather longer than that, but Full Term is what matters for most practical purposes. So the Trinity Term this year began technically on Monday April 20 and ends Monday July 6; but, within that, Full Term is the eight weeks from Sunday April 26 until Saturday June 20.
But, historically, things were much more complicated (and what follows is actually a simplification). The old Latin Statutes knew of two summer terms. There was the Easter Term: Easter Wednesday until the Friday before Pentecost; and the Trinity or "Act" term, the Saturday before Pentecost until the Saturday following the first Tuesday in July. This year, April 8 until May 29; and then May 30 until Saturday 11 July. Hope I've got that right ...
IRONY TRIGGER WARNING.
"Act Term"? During the dark days of popish ecclesiastical tyranny, and even through the oppressions of the absolutist early Stuarts, the University Act was a celebration with many ingredients but, particularly, marked by outrageously satirical attacks upon the Mighty in Academe, Church and State: presided over by an individual called Terrae Filius [the Son of the Earth].
ITW At one particular Act during the reign of Bloody Bess, Terrae Filius found himself ignored. During the night, Someone had placed, on all the seats, newly, secretly, printed copies of the Decem Rationes of S Edmund Campion, which, in the spirit of the day, was full of witticisms directed against the 'Reformers' ... recycling, for example, the rather Private Eye joke about John Calvin having been (physically) branded because he was a homosexual. Everybody was fingering their way through those volumes and sniggering in a way quite disgracefully subversive of Godly Discipline.
ITW Fun, however, doesn't last. "Find out how the Young are enjoying themselves, and put a stop to it". So, following the liberties mercifully secured to us by the Glorious Revolution, enhanced in the fulness of time by the Splendid Enlightenment, the Act became an occasion increasingly dangerous to the Powers that Be (the Convocations of the clergy of Canterbury and York were also suppressed around this time because of the irresponsibility of the Inferior Clergy) with the result that the Act was tamed, emasculated, and made very respectable: in this state it now survives as Encaenia [Commencement], the annual Latin Ceremony (Wednesday after Eighth Week) when Honorary Degrees are conferred upon distinguished visitors ... er ... who mostly seem to be North Americans ... what is the Yankie dialect term for "the Great and the Good"?