## Wikipedia - ثابت العازل (ar) relative permittivity, $$\varepsilon_{\text{r}}$$

https://doi.org/10.1351/goldbook.R05273
Ratio of the @[email protected] in vacuum to that in a given medium. It was formerly called the @[email protected]
Source:
Green Book, 2nd ed., p. 14 [Terms] [Book]