Diathermancy

Part of speech: noun

Definitions

1. The property of a material that allows radiant heat, such as infrared radiation, to pass straight through it without being absorbed
2. The ability of a medium to let heat rays travel across it rather than taking them in along the way
3. How readily a substance lets thermal radiation penetrate it, a quality essentially equivalent to transparency to heat

Etymology: Diathermancy is the property of a substance that lets radiant heat pass straight through it, the way glass lets sunlight through. The term came into English from French "diathermansie," and its parts are easy to read: "dia-" meaning "through," the Greek "thermansis," or "heating," and the English suffix "-ancy," which forms nouns of quality. Taken together, it describes the capacity to be passed through by heat rays. The Greek root goes back to "thermainō," "to heat," which is also the source of "thermos" and "thermometer." Where "diathermancy" differs is in its focus: it describes how heat moves through a body rather than how hot the body is. The word is a technical coinage built from Greek parts, so its meaning was fixed by physicists studying radiant heat rather than by everyday speakers.

Synonyms: diathermanity

Antonyms: athermancy