[{"Bold_text": "adjective", "List Items": ["of or relating to the Silures their country.", "Geology.noting or pertaining to a period of the Paleozoic Era, occurring from 425 to 405 million years ago, notable for the advent of air-breathing animals and terrestrial plants."]}, {"Bold_text": "noun", "List Items": ["Geology.the Silurian Period or System of rocks."]}]