1. A dream arousing feelings of intense fear, horror, and distress.
2. An event or experience that is intensely distressing.
3. A demon or spirit once thought to plague sleeping people.
[Middle English, a female demon that afflicts sleeping people : night, night; see NIGHT + mare, goblin (from Old English; see mer- in the Appendix of Indo-European roots).]
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.