R and Radioactivity unit

R noun - A unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air.

Radioactivity unit and r are semantically related. In some cases you can use "Radioactivity unit" instead a noun "R".

Radioactivity unit noun - A measure of radioactivity.

R and radioactivity unit are semantically related. Sometimes you can replace term "R" with "Radioactivity unit", this terms are similar.