The river was called "An Ruirthech", meaning "fast (or strong) runner" before it was called Liffey. The word "Liphe" (or "Life") was the name of the plain ("flat area of land") through which the river flowed but was later used to name the river itself. It was also known as the Anna Liffey, possibly because of the Irish for "River Liffey" - "Abhainn na Life" which sounds like "Anna Liffey" in English.