Reading stones refer to a handheld concave lens that is used to magnify text for easier reading. There are various synonyms for a reading stone, which often depend on its shape, size, or usage. For example, 'magnifying glass' is a commonly used term for a reading stone that is round and held close to the text. 'Loupes' is another term that typically refers to reading stones with a loop design or those used for jewelry-making. Meanwhile, 'visual aid' is a broader term that encompasses not only reading stones but also other tools like reading glasses and electronic magnifiers. Whatever the term, reading stones provide a handy solution for those with visual difficulties when reading.