noun the day after Resurrection, Judgment Day etc, i.e. a day that will never come in this lifetime. C. L. Apperson, in English Proverbs and Proverbial Phrases, calls it 'a day neither before nor after Christmas'. Brewer's Dictionary of Phrase and Fable (1870) points out that there never was such a saint as St Tibb, hence the use of the term as a synonym for 'never' CANADA, 1999