Em`is*siv"i*ty (?), n. Tendency to emission; comparative facility of emission, or rate at which emission takes place; specif. (Physics), the rate of emission of heat from a bounding surface per degree of temperature difference between the surface and surrounding substances (called by Fourier external conductivity).

Em`is*siv"i*ty (?), n. Tendency to emission; comparative facility of emission, or rate at which emission takes place, as of heat from the surface of a heated body.

Em`is*siv"i*ty (?), n. Tendency to emission; comparative facility of emission, or rate at which emission takes place; specif. (Physics), the rate of emission of heat from a bounding surface per degree of temperature difference between the surface and surrounding substances (called by Fourier external conductivity).