'Pilegesh' is a Hebrew term for a concubine, a marital companion of social and legal status inferior to that of a wife. Among the Israelites, men commonly acknowledged their concubines, and such women enjoyed the same rights in the house as legitimate wives.

In the Hebrew of the contemporary State of Israel, 'pilegesh' is often used as the equivalent of the English word "mistress"—i.e., the female partner in extramarital relations—regardless of legal recognition.

Several biblical figures had concubines when they were not able to create natural children with their wives. The most famous example of this was with Abraham and Sarah. Sarah gave her maidservant Hagar to Abraham while maintaining ownership of both maidservant and offspring. Their union produced Ishmael. Hagar gained the status of full wife in regards to Abraham, but nonetheless Sarah retained the status of main wife.

Any offspring created as a result of a union between a 'pilegesh' and a man were on equal legal footing with children of the man and his wife.

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