1. An outer cover: a shell casing; a tire casing.
2. The frame or framework for a window or door.
3. A metal pipe or tube used as a lining for a water, oil, or gas well.
4. A membranous case, often made of animal intestine, used to contain sausage or other processed meat.
5. A narrow passage for a rod or cord, as in a curtain or the waistband of a garment, made by folding over a small strip of fabric at its edge along its width and sewing it in place.
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.