1. The International System unit of dose equivalent, equal to the dose equivalent when the absorbed dose of ionizing radiation multiplied by stipulated dimensionless factors is 1 joule per kilogram. Abbreviated Sv.

2. A unit of radiation dose, equal to the dose delivered by a point source of 1 milligram of radium, enclosed in a platinum container with walls 0.5-millimeter thick, to a sample at a distance of 1 centimeter over a period of 1 hour; equal to approximately 8.38 roentgens. Also known as millicurie-of-intensity- hour.