top-level
adjective [ before noun ] uk/ˌtɒpˈlev.əl/ us/ˌtɑːpˈlev.əl/
最高阶层的，最高级的
A top-level activity is one in which the most important people in an organization or country take part.
top-level talks/negotiations/discussions 最高级会谈／谈判／讨论