attenuation

Short definition from Wiktionary

Noun

1. 1
   A gradual diminishing of strength.
2. 2
   A reduction in the level of some property with distance, especially the amplitude of a wave or the strength of a signal.
3. 3
   A weakening in the virulence of a pathogen or other microorganism.
4. 4
   The tapering of a leaf etc to a fine point.
5. 5
   A fabrication process in which a material is stretched out into a thin shape.
6. 6
   The reduction of the active principles of medicines to minute doses.
7. 7
   The proportion of sugar that is converted to ethanol by a yeast.