DBpedia (from “DB” for “database”) is a project aiming to extract structured content from the information created as part of the Wikipedia project. This structured information is then made available on the World Wide Web. DBpedia allows users to semantically query relationships and properties associated with Wikipedia resources, including links to other related datasets. DBpedia has been described by Tim Berners-Lee as one of the more famous parts of the decentralized Linked Data effort.
For me, “semantic” generally refers to the W3C specified “semantic web” technologies, which include DBpedia. Natural language, or “conversational”, *dialog systems* may or may not be “question answering systems” and may or may not be “semantic” per se.
As far as I know, there is currently no general purpose dialog system available based primarily on conventional “semantic web” technologies; however, I believe that‘s “Digital Aristotle” Project Halo is or was heavily based on DBpedia.
See also my quick and dirty webpages: