sat·u·ra·tion (săchˌə-rāˈshən)

1. The act or process of saturating.
2. The condition of being saturated.
3. The condition of being full to or beyond satisfaction; satiety.
4. Filling of all the available sites on an enzyme molecule by its substrate, or on a hemoglobin molecule by molecular oxygen or carbon monoxide.
5. In optics, the degree which colors of the same wavelength are differentiated from one another on the basis of purity which correlates with the amount of white present, such as red from pink.