Yes, caste is a Scrabble word!

Noun

1. Social status or position conferred by a system based on class

2. (Hinduism) a hereditary social class among Hindus; stratified according to ritual purity

3. A social class separated from others by distinctions of hereditary rank or profession or wealth

4. In some social insects (such as ants) a physically distinct individual or group of individuals specialized to perform certain functions in the colony