A broad, shallow, generally flat-floored volcanic crater of explosive origin that is often filled with water.
[German, from Vulgar Latin *mara, standing water, lake, from Latin mare, sea; see MARE2.]
(click for a larger image)maar
Eifel region of Germany
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.