noun Etymology: probably from thermal resistance Date: 1948 a measure of resistance to the flow of heat through a given thickness of a material (as insulation) with higher numbers indicating better insulating properties
R-VALUE
Meaning of R-VALUE in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012