v. at·ten·u·at·ed, at·ten·u·at·ing, at·ten·u·ates
1. To make slender, fine, or small: The drought attenuated the river to a narrow channel.
2. To reduce in force, value, amount, or degree; weaken: Medicine attenuated the fever's effect.
3. To lessen the density of; rarefy.
4. Biology To make (bacteria or viruses) less virulent.
5. Electronics To reduce (the amplitude of an electrical signal) with little or no distortion.
To become thin, weak, or fine.
1. Reduced or weakened, as in strength, value, or virulence.
2. Botany Gradually tapering to a slender point.
[Latin attenuāre, attenuāt- : ad-, ad- + tenuāre, to make thin (from tenuis, thin; see ten- 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.