An Etymological Dictionary of Astronomy and Astrophysics

An SI unit of absorbed radiation dose. One gray is equivalent to an energy absorption of 1 → joule/kg. It has replaced the → rad (rd), an older standard. One gray is equivalent to 100 rad. See also → sievert (Sv).

See also: Named for Louis Harold Gray (1905-1965), British radiologist and the pioneer of use of radiation in cancer treatment.