loaf [OE] Originally loaf meant ‘bread’ as well as ‘a shaped quantity of bread’. In the British expression to use your loaf, ‘use your common sense’, loaf probably comes from the rhyming slang phrase loaf of bread meaning ‘head’. It is first recorded in a 1920s dictionary of army and navy slang as ‘Loaf, head, e.g., Duck your loaf, i.e., keep your head below the parapet’. For to loaf see german words. See also bread, lady, lord.