Plants and animals have played an important role in human life for as long as they've all existed. In fact, without the plants and animals that humans have used for food, labor, tools and companionship over countless generations, society could not have advanced to the point it has today.
Viscosity refers to the speed at which a substance can flow (i.e. the thickness of the substance/its ability to flow). I think that's the closest the English language gets.
