From The Collaborative International Dictionary of English v.0.48 [gcide]:
2. (Eccl.) A church festival celebrated on the 6th of January, the twelfth day after Christmas, in commemoration of the visit of the Magi of the East to Bethlehem, to see and worship the child Jesus; or, as others maintain, to commemorate the appearance of the star to the Magi, symbolizing the manifestation of Christ to the Gentles; Twelfthtide.
From WordNet (r) 3.0 (2006) [wn]:
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