صفت ( adjective )
• : تعریف: of, relating to, or designating the geological period between the Cambrian and Silurian of the Paleozoic Era, from approximately 500 million to 440 million years ago, when marine invertebrate animals were abundant.
اسم ( noun )
• : تعریف: the Ordovician Period, or the rock formations that date from that time.