noun, plural black·bod·ies. Physics.
- a hypothetical body that absorbs without reflection all of the electromagnetic radiation incident on its surface.
- A theoretically perfect absorber and emitter of every frequency of electromagnetic radiation. The radiation emitted by a blackbody is a function only of its temperature.
An object that can absorb and send off radiation with complete efficiency — that is, it reflects (see reflection) none of the radiation that falls on it. The higher the object’s temperature, the higher the frequency of the radiation it gives off.