from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Lasting three days.
- adj. Happening every third day.
- n. An event lasting three days.
from the GNU version of the Collaborative International Dictionary of English
- adj. Lasting three lays; also, happening every third day.
from The Century Dictionary and Cyclopedia
- Lasting three days, or happening every third day.
From triduum ("space of three days"). (Wiktionary)
In the following night the storm terminated its triduan existence some time between darkness and dawn.