[ noun ] an extreme bellicose nationalist <noun.person>
Jingo \Jin"go\, n.; pl. {Jingoes}. [Said to be a corruption of St. Gingoulph.] 1. A word used as a jocular oath. ``By the living jingo.'' --Goldsmith.
2. A statesman who pursues, or who favors, aggressive, domineering policy in foreign affairs; a bellicose superpatriot or chavinist. [Cant, Eng.] [1913 Webster +PJC]
Note: This sense arose from a doggerel song which was popular during the Turco-Russian war of 1877 and 1878. The first two lines were as follows:
We don't want to fight, but by Jingo if we do, We 've got the ships, we 've got the men, we 've got the money too.