- The giving off of heat rays; a perfect “black body” has an e. of 1, a highly polished metallic surface may have an e. as low as 0.02.
* * *emis·siv·i·ty .em-ə-'siv-ət-ē, .ē-.mis-'iv- n, pl -ties the relative power of a surface to emit heat by radiation: the ratio of the radiant energy emitted by a surface to that emitted by a blackbody at the same temperature
* * *emis·siv·i·ty (e″mĭ-sivґĭ-te) the ratio of emissive power (of radiant energy) of a surface to that of a black surface having the same temperature.
Medical dictionary. 2011.