Significance of Liffey's Name- The River Liffey
I'm not sure if the name Liffey is a nickname, but there is a river in Ireland called the River Liffey, which flows through the center of Dublin. Liffey means "a life" in Irish.
The river was previously named An Ruirthech, meaning "fast (or strong) runner".[1] The word Liphe (or Life) referred originally to the name of the plain through which the river ran, but eventually came to refer to the river itself. [2] It was also known as the Anna Liffey,[3] possibly from an Anglicization of Abhainn na Life, the Irish phrase that translates into English as River Liffey.[4]
http://en.wikipedia.org/wiki/River_Liffey