1. the ability of a substance to spread out or disperse through another medium
Usage: physics; chemistry
2. a measure of how quickly heat, mass, or momentum spreads through a material
Usage: technical; engineering

Examples

• The thermal diffusivity of copper is much higher than that of wood.
• Scientists measured the diffusivity of the gas through the membrane.
• High diffusivity allows heat to spread quickly through the metal.
• The diffusivity of salt in water depends on temperature.
• Engineers calculate diffusivity to design better heat exchangers.
• Mass diffusivity determines how fast pollutants spread in groundwater.