• Webster's Revised Unabridged Dictionary
    • a Diathermanous Having the property of transmitting radiant heat; diathermal; -- opposed to athermanous.
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Century Dictionary and Cyclopedia
    • diathermanous Freely permeable by heat. The term is specifically applied to certain substances, such as crystalline pieces of rock-salt, etc., which suffer radiant heat to pass through them, much in the same way as transparent or diaphanous bodies allow of the passage of light. See absorption. Also diathermal, diathermic, diathermous.
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Webster's Revised Unabridged Dictionary
Gr. to warm through; dia` through + to warm, warm


In literature:

Rock-salt is diathermanous to heat from nearly all sources.
"The New Gresham Encyclopedia" by Various