This term had been a generic one as well, but after the title was given to the mother (Naka) who gave birth to Hideyoshi, the term came to be used for indicating her alone.
こちらも元は単なる総称だったが、これが秀吉の生母・大政所（なか）に贈られてからは専ら彼女のことを指す語となった。