Either of two movable flaps on the wings of an airplane that can be used to control the plane's rolling and banking movements.
[French, diminutive of aile, wing, from Old French, from Latin āla.]
(click for a larger image)aileron
To bank to the left, a pilot must raise the left aileron and lower the right aileron.
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.