mas·to·don (măstə-dŏn′) also mas·to·dont (-dŏnt′)
Any of several very large, extinct proboscidian mammals of the family Mammutidae of the Miocene, Pliocene, and Pleistocene Epochs, resembling elephants but having molar teeth of a different structure.
[New Latin Mastodōn, genus name : Greek mastos, breast, nipple + Greek odōn, tooth (from the nipple-shaped protrusions on the crowns of its molars); see dent- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.