1. The act of attenuating.
2. Diminution of virulence in a strain of an organism, obtained through selection of variants that occur naturally or through experimental means.
3. Loss of energy of a beam of radiant, ultrasound, or other energy because of absorption, scattering, beam divergence, and other causes as the beam propagates through a medium.
4. Regulation of termination of transcription; involved in control of gene expression in specific tissues.
The information shown above for attenuation is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.