This paper argues that synthetic compounds in English (truck driver) are licensed by the semantics rather than the syntax. They are made fully interpretable by their affix, which binds the noun's entity argument, and often the world argument to allow de dicto interpretations. Meanwhile, the verbs that they are built from (*truck-drive) lack such a binder, and are not properly interpreted unless the semantic context provides some other binder. Other contexts include oblique linkers (hand-wash), lexicalization (world-build). Finally, supporting evidence is found with Kiowa incorporation, which also forbids object compounding without the independently-required presence of a binder.