1. A short coat usually extending to the hips.
2. An outer covering or casing, especially:
a. The skin of a potato.
b. The dust jacket of a book or phonograph record.
c. An insulation covering for a steam pipe, wire, boiler, or similar part.
d. An open envelope or folder for filing papers.
e. The outer metal shell or case of a bullet.
3. A piece of jewelry or other ornament that attaches to an earring stud.
tr.v. jack·et·ed, jack·et·ing, jack·ets
To supply or cover with a jacket.
[Middle English jaket, from Old French jaquet, diminutive of jaque, short jacket, tunic, from jacques, nickname for French peasants, from the name Jacques; see JACK.]
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.