1. of, relating to, or denoting the second period of the Paleozoic Era, lasting from approximately 485 to 444 million years ago, characterized by the diversification of marine life.
Usage: geology; paleontology

1. the Ordovician Period or System; the second period of the Paleozoic Era.
Usage: geology; paleontology

Examples

• The Ordovician period saw the emergence of many new marine species.
• Ordovician rocks contain abundant fossils of trilobites and early fish.
• During the Ordovician, most life on Earth existed in the oceans.
• Geologists study Ordovician deposits to understand ancient marine ecosystems.
• The Ordovician ended with a major extinction event that affected marine life.