1. Any of various venomous snakes of the family Viperidae, having a thick heavy body and a single pair of long hollow fangs, especially the Eurasian and African species of the subfamily Viperinae, which lack the sensory pits of the pit vipers.
2. Any of several harmless snakes sometimes believed to be venomous.
3. A person regarded as malicious or treacherous.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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.