triduum /tridˈū-əm or trīˈdū-/ (esp RC)

1. A space of three days
2. A period of prayer or religious celebration lasting three days

• brightening agents
• brightens
• brighter
• brightest
• bright-eyed and bushy-tailed
• bright-field illumination
• brightly
• brightness
• brightnesses
• brights
• Bright's disease
• brightsome
• bright spark
• brightwork
• bright young thing
• brigs
• brigue
• brigued
• brigues
• briguing
• briguings
• brill
• briller
• brillest
• brilliance