from The American Heritage® Dictionary of the English Language, 4th Edition

  • transitive v. To make slender, fine, or small: The drought attenuated the river to a narrow channel.
  • transitive v. To reduce in force, value, amount, or degree; weaken: Medicine attenuated the fever's effect.
  • transitive v. To lessen the density of; rarefy.
  • transitive v. Biology To make (bacteria or viruses) less virulent.
  • transitive v. Electronics To reduce (the amplitude of an electrical signal) with little or no distortion.
  • intransitive v. To become thin, weak, or fine.
  • adj. Reduced or weakened, as in strength, value, or virulence.
  • adj. Botany Gradually tapering to a slender point.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • v. To reduce in size, force, value, amount, or degree.
  • v. To make thinner, as by physically reshaping, starving, or decaying.
  • v. To weaken.
  • v. To rarefy.
  • v. To reduce the virulence of a bacteria or virus.
  • v. To reduce the amplitude of an electrical signal.
  • adj. Gradually tapering into a petiole-like extension toward the base.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Made thin or slender.
  • adj. Made thin or less viscid; rarefied.
  • intransitive v. To become thin, slender, or fine; to grow less; to lessen.
  • transitive v. To make thin or slender, as by mechanical or chemical action upon inanimate objects, or by the effects of starvation, disease, etc., upon living bodies.
  • transitive v. To make thin or less consistent; to render less viscid or dense; to rarefy. Specifically: To subtilize, as the humors of the body, or to break them into finer parts.
  • transitive v. To lessen the amount, force, or value of; to make less complex; to weaken.

from The Century Dictionary and Cyclopedia

  • To make thin or slender; reduce in thickness; wear or draw down: as, an attenuated thread or wire.
  • To reduce by comminution or attrition; make small or fine: as, extremely attenuated particles of dust or flour.
  • To make thin or rare; reduce in density; increase the fluidity or rarity of.
  • To lessen in complexity or intensity; reduce in strength or energy; simplify; weaken: as, the attenuated remedies of the homeopathists.
  • Figuratively, to weaken or reduce in force, effect, or value; render meager or jejune; fine down.
  • To lessen; diminish: said of number. Howell.
  • To become thin, slender, or fine; diminish; lessen.
  • In brewing and distilling, to undergo the process of attenuation. See attenuation, 4.
  • Slender; thin.
  • In botany, tapering gradually to a narrow extremity.
  • Of thin consistency; dilute; rarefied.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • v. weaken the consistency of (a chemical substance)
  • adj. reduced in strength
  • v. become weaker, in strength, value, or magnitude


Latin attenuāre, attenuāt- : ad-, ad- + tenuāre, to make thin (from tenuis, thin; see ten- in Indo-European roots).
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin attenuāre, from attenuāt-, at- = ad-, ad- ("to") + tenuāre ("to make thin"), tenuis ("thin"). (Wiktionary)



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  • He saw plainly that he was doomed to grow ever feebler and that each day that passed would attenuate his hold on life.

    Donald Keene, The Diaries of Masaoka Shiki

    November 19, 2011