a. Liable or subject to death; not immortal: mortal beings.
b. Of or relating to humans as being subject to death: "When we have shuffled off this mortal coil" (Shakespeare).
a. Causing death; fatal: a mortal wound. See Synonyms at fatal.
b. Fought to the death: mortal combat.
c. Relentlessly hostile; implacable: a mortal enemy.
a. Of great intensity or severity; dire: mortal terror.
b. Conceivable; imaginable: no mortal reason for us to go.
c. Used as an intensive: a mortal fool.
[Middle English, from Old French, from Latin mortālis, from mors, mort-, death; see mer- in the Appendix of Indo-European roots.]
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.