1. biometrics the number of occurrences of a given type of event or the number of members of a population falling into a specified class 2. biometrics the number of plots, counts, or intervals in which an object (e.g., species) is detected —see incidence, population density, severity 3. ecology the number of individuals in a community 4. ecology the proportion of samples in which a species occurs —see constancy 5. range management the ratio between the number of sample units that contain a species and the total number of sample units —see density This definition last updated 10/24/2008