Supporter of policy favouring war; a blustering patriot.
This is a bit of a judgmental definition, if you ask me. If "jingo" was a gag word (or, as the dictionaries say, a "jocular" word) then I might not think anything of it. But "blustering" suggests emptiness and haught when something like "grandiloquent" or "verbose" might define the word with less bias. I have understood jingoism to be something fanatical but nevertheless interesting. My earliest associations for that word involved individuals who knew their stuff so well that they were unassailable in their command of the political issues at hand. For some reason I also associate this word with the American composer Frederic Rzewski. I think this is simply because I first heard "jingoism" in a lecture about this composer. Rzewski wrote politically themed music ("Apolitical Intellectuals" is among my favorite 20th century songs) but I do not remember if he himself was described as a jingoist or if the word was directed at someone or something else in the context of the lecture.