Duner is a word that generally refers to a type of sandy terrain, often associated with desert environments. However, there are a number of different synonyms that can be used to describe this type of landscape. One such synonym is sand dunes, which conveys the same basic meaning as duner, but is perhaps more commonly used in everyday language. Other potential synonyms might include desert hills, sandy ridges, or even simply sand land. Ultimately, the choice of which synonym to use will depend on factors such as the context of the conversation and the intended audience.