Dictionary.com
Thesaurus.com

Oak-apple Day

British  

noun

  1. (in Britain) May 29, the anniversary of the Restoration (1660), formerly commemorated by the wearing of oak apples or oak leaves, recalling the Boscobel oak in which Charles II hid after the battle of Worcester

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012