The act of emitting or sending forth something, such as a gas, light, or radiation. The emanation of smoke from the factory chimneys was visible from miles away.
Something that is emitted or sent forth; an emission. The mysterious emanation from the cave intrigued the explorers.
In philosophy, a process by which something flows out from a source or origin. The philosopher discussed the emanation of ideas from the mind.
Physics (historical). A radioactive gaseous product, especially radon, produced by the disintegration of radium, thorium, or actinium. Early researchers collected the emanation from radium salts to measure levels of radioactivity.