a. Sour fermented dough used as leaven in making bread.
b. Bread made from such a leaven.
2. An early settler or prospector, especially in Alaska and northwest Canada.
[Sense 2, from an association with using pieces of sourdough to leaven bread in the winter.]
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.