Haddest rights is an old English term that refers to having legitimate claims or entitlements to something. There are several synonyms or phrases that can be used in place of this archaic term, such as being entitled, having legal rights, having a valid claim, having just cause or possessing valid ownership. These phrases are more commonly used in modern times and can be applied in various contexts. For instance, someone may be entitled to compensation for work done, have legal rights to an inheritance, have a valid claim to property or possess valid ownership of a particular item. Using these synonyms can help to make language more concise and easy to understand.