From The Collaborative International Dictionary of English v.0.48:
Jingo \Jin"go\, n.; pl. Jingoes. [Said to be a corruption of
St. Gingoulph.]
[1913 Webster]
1. A word used as a jocular oath. "By the living jingo."
--Goldsmith.
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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:
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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.
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