1. Of, relating to, or being the period of geologic time from about 146 to 66 million years ago, the third and most recent period of the Mesozoic Era. The Cretaceous Period is characterized by the formation of modern continents from the supercontinent Pangaea and by the development of flowering plants. The Period ended with the sudden extinction of the dinosaurs and many other forms of life. See Table at geologic time.
2. cretaceous Of, containing, or resembling chalk.
The Cretaceous Period.
[From Latin crētāceus, chalky, from crēta, chalk, from Crēta (terra), Cretan (earth).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.