Tom Coates gets the Oxford English Dictionary to provide a draft definition of "weblog":
"A frequently updated web site consisting of personal observations, excerpts from other sources, etc., typically run by a single person, and usually with hyperlinks to other sites; an online journal or diary."But which would your prefer, the stodgy static OED version, or the living Wikipedia definition?
Better yet, there isn't a definition of weblog in Wiktionary yet. Here's your chance to seed an immortal root.
Update: Jason says its "weblog" not "web log"