from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A period of three days (especially in Roman Catholic liturgy).
from The Century Dictionary and Cyclopedia
- n. A space of three days.
- n. In the Roman Catholic Church, prayers for the space of three days as a preparation for keeping a saint's day, or for obtaining some favor of God by means of the prayers of a saint.
From Latin triduum, from Latin tres ("three") (from Ancient Greek τρία (tria)) + dies ("day"). (Wiktionary)