▪ I. gray etc.:
see grey.
▪ II. gray, n.2
(greɪ)
[The name of Louis Harold Gray (1905–65), English radiobiologist.]
A unit of absorbed dose of ionizing radiation, corresponding to the absorption of 1 joule of energy per kilogramme of absorbing material; 100 rads. Symbol Gy.
| 1975 Physics Bull. Mar. 105/1 The CIPM will recommend to the CGPM that the si unit of activity should be given the name ‘becquerel’, symbol Bq, and the si unit of absorbed dose the name ‘gray’, symbol Gy. 1976 [see Becquerel n. 2]. 1986 New Scientist 12 June 29/3 After a dose of between 8 and 12 grays, the person would suffer diarrhoea and vomiting, but would die from failure of the bone marrow unless rescued by a bone-marrow transplant. 1989 Times 4 Aug. 13/4 Absorbed radiation dosage is measured in units called grays (Gy). A dose of 3–4 Gy will kill 50 per cent of any given group of people. |