This chapter defines the semantics of the FunnelWeb program. As stated at the start of this chapter, this document takes precedence over the FunnelWeb program. While the definition of FunnelWeb in this chapter is reasonably solid, it is far from watertight, and it is hoped that it can be tightened further in future versions. All constructive criticism will be gratefully received by the author Ross Williams (ross@spam.adelaide.edu.au).