a. A vertically hinged plate of metal, fiberglass, or wood mounted at the stern of a ship or boat for directing its course.
b. A similar structure at the tail of an aircraft, used for effecting horizontal changes in course.
2. A controlling agent or influence over direction; a guide.
[Middle English ruder, from Old English rōther, steering oar; see erə- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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.