The term 'Radiation Measure' can be broken down into two parts: REM (3 letters) and Roentgen (8 letters). REM stands for 'Roentgen Equivalent Man', which is a unit of measurement used to measure the biological effects of radiation on humans. Roentgen is a unit of measurement used to measure the amount of radiation absorbed by an object. It is named after Wilhelm Roentgen, who discovered X-rays in 1895.