Attenuation

1. n. The process of weakening in intensity; diminution of virulence; as, the attenuation of virus.
2. n. The act or process of making slender, or the state of being slender; emaciation.
3. n. The act of attenuating; the act of making thin or less dense, or of rarefying, as fluids or gases.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.