Brandagamba
Within Tolkien's history, the Hobbits of the family known as the Brandybucks did not actually use that name. Rather, like many other words and names within Tolkien's tales, 'Brandybuck' is an anglicised version of a more alien and unusual-sounding original name. In this case, the clan of the Masters of Buckland in fact belonged to the family known as Brandagamba.
On the same principle, the river-name 'Brandywine' is adapted from the original 'Branda-nîn', meaning 'border-water', and it is from this name that the branda- element of Brandgamba originates (it means 'borderland', a reference to Buckland to the extreme east of the Shire). The -gamba segment is equivalent to 'buck', and is also found in the older form Zaragamba (which translates into English as 'Oldbuck').