Pronunciation: (tā dā'oom, -um, tē dē'um), [key]
1. (italics) an ancient Latin hymn of praise to God, in the form of a psalm, sung regularly at matins in the Roman Catholic Church and, usually, in an English translation, at Morning Prayer in the Anglican Church, as well as on special occasions as a service of thanksgiving.
2. a musical setting of this hymn.
3. a service of thanksgiving in which this hymn forms a prominent part.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.