design- is a
noun prefix in
Dutch
meaning '
modern looking,
trendy and
expensive'.
For instance, designmeubels ('design furniture') means 'modern looking, trendy, expensive furniture'.
This prefix is a particular use of the noun design, a loan word from English, which means 'interior design'. As such it is a synonym for the older term, binnenhuisarchitectuur (lit. 'inner house architecture', but, like most English loan words for which Dutch synonyms exist, design is the more trendy word to use.
The Dutch translation of 'design', incidentally, is ontwerp.