1. A close-fitting jacket, with or without sleeves, worn by European men from the late 1300s to around 1650.
a. A pair of similar or identical things.
b. A member of such a pair.
c. Physics A multiplet with two members.
3. Linguistics One of two words derived from the same historical source by different routes of transmission, such as skirt from Scandinavian and shirt from English.
4. An imitation gem composed of two parts, as of an inferior stone layered beneath a precious gem.
5. doublets Games A throw of two dice in which the same number of dots appears on the upper face of each.
[Middle English, from Old French, diminutive of double, double; see DOUBLE.]
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.