صفت ( adjective )
• : تعریف: of, relating to, or designating the geological period between the Ordovician and Devonian of the Paleozoic Era, from approximately 440 million to 400 million years ago, when coral reefs began forming and land plants and air-breathing animals appeared.
اسم ( noun )
• : تعریف: the Silurian Period, or the rock formations that date from that time.