quad·rup·let (kwŏ-drŭplĭt, -drplĭt, kwŏdrə-plĭt)
1. One of four offspring born in a single birth.
2. A group or combination of four associated by common properties or behavior.
3. Music A group of four notes having the time value of three notes of the same kind.
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.