The curie (Ci) is a measure of the number of disintegrations events per unit time in a mass of radioactive material. One Ci is 37 x 10^9 events per second, or in computer terms 37 gigahertz. The number 2.2 x 10^12 disintegrations per minute is also used. The symbol ^ is used throughout to indicate exponentiation. Note that the Ci is a measure of the activity of some mass or quantity of material. It is not a material property such as specific activity which is measured in curies per gram (Ci/g). Also note that the numerical magnitude of activity is not itself a measure of relative hazard because the hazard evaluation needs to consider the type and energy of the disintegrations, not just the number of disintegrations.
Up-to-date usage is replacing the curie with the becquerel (Bq) where one Bq is defined as one disintegration per second, so one Ci = 37 x 10^9 Bq .