The Collaborative International Dictionary of English v.0.48:
hot cross bun \hot" cross bun`\ (-b[u^]n`), n. A bun or cake marked with a cross of icing, and intended to be eaten on Good Friday; called also cross bun. [1913 Webster +PJC]WordNet (r) 3.0 (2006):
cross bun n 1: moderately sweet raised roll containing spices and raisins and citron and decorated with a cross-shaped sugar glaze [syn: cross bun, hot cross bun]