Where does the word dearth come from?

The facts about the history of the word dearth are quite simple: the word derives from the Middle English form derthe, which has the same meaning as our modern term. That Middle English form is assumed to have developed from an Old English form that was probably spelled dierth and was related to dēore, the Old English form that gave us the word dear. (Dear also once meant "scarce," but that sense of the word is now obsolete.) Dearth, in one form or another, has been used to describe things that are in short supply since at least the 13th century, when it often referred to a shortage of food.