a. The hue of the long-wavelength end of the visible spectrum, evoked in the human observer by radiant energy with wavelengths of approximately 630 to 750 nanometers; any of a group of colors that may vary in lightness and saturation and whose hue resembles that of blood; one of the additive or light primaries; one of the psychological primary hues.
b. A pigment or dye having a red hue.
c. Something that has a red hue.
a. often Red A Communist.
b. A revolutionary activist.
3. The condition of being in debt or operating at a loss: The firm has been in the red all year.
adj. red·der, red·dest
1. Having a color resembling that of blood.
2. Reddish in color or having parts that are reddish in color: a red dog; a red oak.
a. Having a reddish or coppery skin color.
b. often Red Often Offensive Of or being a Native American.
4. Having a ruddy or flushed complexion: red with embarrassment.
5. Relating to or being a red state.
6. often Red Communist.
[Middle English, from Old English rēad; see reudh- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.