From the Hebrew name רָחֵל (Rachel) meaning "ewe". In the Old Testament this is the name of the favourite wife of Jacob and the mother of Joseph and Benjamin. She was the younger sister of Jacob's first wife Leah.
The name was common among Jews in the Middle Ages, but it was not generally used as a Christian name in the English-speaking world until after the Protestant Reformation. A notable bearer was the American conservationist Rachel Carson (1907-1964).