Quid is British informal for a pound sterling, dates from the late 1600s and was used for older coins known as sovereigns. Despite many different etymological attempts and theories, the origin of quid remains unknown. Eric Partridge ventures that it derives from the Latin quid meaning ‘what’, in the sense of ‘the wherewithal’ meaning money. Because quid has always been classed as low class slang, a Latin origin is extremely doubtful. The plural, quids, was in general use until the mid-19th century when it became obsolete. Since then, quid is now used for both singular and plural senses of the word.