1. A group or set of three of one kind.
2. One of three children born at one birth.
3. A group of three lines of verse.
4. Music A group of three notes having the time value of two notes of the same kind. Also called tercet.
5. Physics A multiplet with three components.
6. Genetics A unit of three successive nucleotides in a molecule of DNA or RNA that codes for a specific amino acid; a codon or anticodon.
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.