Phenotypic heterogeneity is a term that refers to the variation in characteristics that are observed within a population. Synonyms for this term include phenotypic diversity, phenotypic variability, and phenotypic variation, which all describe the range of physical, behavioral, and other traits that can be exhibited by individuals in a given group. Other related terms include phenotypic plasticity, which refers to the ability of an organism to change its phenotype in response to environmental cues, and phenotypic differentiation, which refers to the process by which populations diverge in their physical traits over time. Overall, these terms underscore the complexity and diversity that exists within biological systems.