noun

• Initialism of electron spin resonance. [(physics) The absorption of radiation by species having unpaired electrons when placed in a magnetic field that is used spectroscopically to detect and study free radicals]
• (hematology) Initialism of erythrocyte sedimentation rate. [(hematology) The rate (usually expressed in millimeters per hour) at which red blood cells precipitate in a vertical tube over a period of one hour, often determined as a screening test for the presence of inflammation.]
• (software) Initialism of extended-support release.