There are four terms in the year, viz. […] 3. Easter term, which begins on the tenth day after Easter Sunday, and ends on the day before Whitsunday.
1813, “University Terms, and How Many are Required to be Kept for each Degree”, in The Oxford University Calendar, for the Year 1813, Oxford: Printed by Munday and Slatter, for J. Parker; and F[rancis] C[harles] and J[ames] Rivington, London, page 65