I've been workin' on the railroad, all the livelong day. So goes the American folk standard, and nowadays when we encounter the word livelong it is typically in the phrase "all the livelong day" or something similar. Although we don't see "livelong" much in prose anymore poets still love the word, possibly for its two distinct, alliterative syllables. Despite the resemblance, "livelong" does not mean the same thing as "lifelong" (as in "a lifelong friend"). In fact, the words are not closely related: the "live" in livelong derives from "lef," a Middle English word meaning "dear or beloved."