1. members of a third order of a religious organization, typically laypeople who follow a modified rule while living in the world
Usage: religious
2. the flight feathers attached to the innermost section of a bird’s wing
Usage: ornithology
3. rocks, deposits, or fossils from the Tertiary period of geological time
Usage: geology

Examples

• The Franciscan tertiaries met monthly to discuss their spiritual practices.
• Many tertiaries balance religious devotion with family and work responsibilities.
• The ornithologist carefully examined the bird’s tertiaries for identification purposes.
• Damaged tertiaries can affect a bird’s flight efficiency.
• The museum displayed fossils from various tertiaries found in the region.
• Geologists studied the tertiaries to understand ancient climate conditions.