Orig. U.S. [UNDER-1 5 b; cf. top-dog TOP sb.1 32.] The beaten dog in a fight; fig. the party overcome or worsted in a contest; one who is in a state of inferiority or subjection.

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1876.  D. Barker, Poems, 103.

        But for me—I never shall pause to ask
    Which dog may be in the right—
For my heart will beat, while it beats at all,
    For the under dog in the fight.

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1887.  Daily Tel., 30 April, 3/3. There is an indefinable expression in his face and figure of having been vanquished, of having succumbed, of having been ‘under-dog’ as the saying is.

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1892.  Daily Chron., 23 June, 5/2. The mission of the Democratic party is to fight for the under dog.

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