I've seen discussions on message boards on the term "nurse girl" used sometimes on Census forms to denote adopted or foster daughters.
However, in the 1871 London Census, I've come across two entries:
George Deighton, Son, Unmarried, aged 16, "Nurse Girl" and also his sister, Emma Deighton, Daughter, Unmarried, aged 14, marked ditto.
Anyone know whether both are likely to have been adopted or fostered? "Nurse Girl" seems an odd description to apply to a 16 year old male.