The news that Apple is facing the world’s largest tax bill prompts an investigation into why we use the word ‘bill’ to refer to a statement of money owed. It turns out that the origins of ‘bill’ can be traced to the Latin word bulla, which means ‘a rounded lump or swelling’. In the days when official documents were sealed with lead, a bulla was the name for the round mass that formed the seal on a document, and it later came to refer to the document itself. Indeed, in the Roman Catholic Church the official documents issued by the Pope are still referred to as ‘papal bulls’. In later Latin, bulla became billa, and in English billa became bill. The word can still refer to various official documents, such as a proposed law that is brought before parliament, although it is now most commonly used for documents that request payment of money.
However, when we use the word ‘bill’ to talk about a bird’s beak, there is a quite different origin at work. In this sense, the word comes from the Anglo-Saxon bile. This is probably related to an Old High German word bil, meaning ‘pickaxe’, on account of a perceived resemblance between the shape of a beak and that of a sharp implement.