a. Not limited by conventional notions of what is practical or feasible; imaginative or visionary: "Proponents of blue-sky thinking often cite the Wright brothers as validation" (David Colman).
b. Unrealistic or impractical: "[The author] shows what is testable physics, what is philosophy's domain, and what is blue-sky nonsense" (Ann Finkbeiner).
2. or blue-skied (-skīd) Having a cloudless sky; clear: a blue-sky day.
intr.v. blue-skied, blue-sky·ing, blue-skies
To hold or express unrealistic or impractical views, especially in estimating something.
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.