"Rosalind" is derived from the Germanic elements hros "horse" and linde "soft, tender". This name was introduced by the Normans to England, though it was not common. During the Middle Ages its spelling was influenced by the Latin phrase rosa linda "beautiful rose". The name was popularised by Edmund Spencer, who used it in his poetry, and by William Shakespeare, who used it for the heroine in his comedy As You Like It (1599).
A "bung" is a stopper especially for the hole through which a cask, keg, or barrel is filled or emptied.
↑To even fit the role that R.A.B did (as Hermione considers), she has to be alive by 1981 to have stolen the locket, which is what the trio have considered her over. Thus, she's born at least before 1964.