The Collaborative International Dictionary of English v.0.48:

Firstling \First"ling\ (f[~e]rst"l[i^]ng), n. [First + -ling.]
   1. The first produce or offspring; -- said of animals,
      especially domestic animals; as, the firstlings of his
      flock. --Milton.
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   2. The thing first thought or done.
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            The very firstlings of my heart shall be
            The firstlings of my hand.            --Shak.
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The Collaborative International Dictionary of English v.0.48:

Firstling \First"ling\, a.
   Firstborn.
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         All the firstling males.                 --Deut. xv.
                                                  19.
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