Caste (biology)

In some eusocial species, individuals of one species live together in colonies. These groups are often called nests or hives. Often there is a division of labour. In Hymenoptera, for example, a hive may have several kinds of females, which by Polyphenism carry out different tasks, and whose bodies are different. 
Such specialized types in one species are known as castes. Castes that are not involved in producing offspring are usually sterile. The term originally comes from the caste-system in Hinduism.