‖ [ L., from te (accus. of tu thou) + Deum, accus. of Deus God. See Thou, and Deity. ] 1. An ancient and celebrated Christian hymn, of uncertain authorship, but often ascribed to St. Ambrose; -- so called from the first words “Te Deum laudamus.” It forms part of the daily matins of the Roman Catholic breviary, and is sung on all occasions of thanksgiving. In its English form, commencing with words, “We praise thee, O God, ” it forms a part of the regular morning service of the Church of England and the Protestant Episcopal Church in America. [ 1913 Webster ]

2. A religious service in which the singing of the hymn forms a principal part. [ 1913 Webster ]

3. A musical setting of the Te Deum{ 1 }. [ Webster 1913 Suppl. ]