Pathway refers to a functional path in the biological networks. It is characterized by its connectivity, orientation, functionality, and dynamics. Thus, not all paths are pathways in biological networks.
In metabolic networks, it is often called metabolic pathways as a whole (Horton et al. 2005). In protein-protein interaction networks, it is often the same as the signaling pathways (Lewin 2003). In gene regulatory networks, it often means the mechanism under which expression quantitative trait loci regulate the expression of their target transcripts. In KEGG (Ogata et al. 1999), the pathway concept is also extended to cell communication, organismal systems, diseases, and drug responses.