a. Of, exhibiting, or afflicted with mental derangement. Not used in psychiatric diagnosis.
b. Characteristic of or associated with persons who are mentally deranged: an insane laugh; insane babbling.
c. Intended for use by such persons: an insane asylum.
2. Having been determined to be in a condition that meets the legal definition of insanity.
3. Immoderate; wild: insane jealousy.
4. Very foolish; absurd: took insane risks behind the wheel.
[Latin īnsānus : in-, not; see IN-1 + sānus, sane, healthy.]
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.