.Ltd.uk is a domain extension that is often used by limited liability companies in the United Kingdom. However, there are a few synonyms for .ltd.uk that can be used interchangeably. One popular synonym is .ltd, which is used by companies in countries like the United States and Australia. Another synonym for .ltd.uk is .ltda, which is commonly used by companies in Latin America. Additionally, some companies may use .ltdco or .ltdli as alternative extensions. Regardless of the specific extension used, these synonyms all signify that the company is a limited liability entity, providing some protection for its owners and shareholders.