Marlin

google

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early 20th century: from marlinspike (with reference to its pointed snout).

wiktionary

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A contraction of marlinspike, named so because of its pointed snout.

etymonline

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marlin (n.)

large marine game-fish, 1917, shortening of marlinspike fish (1907), from marlinspike, name of a pointed iron tool used by sailors; the fish was so called from the shape of its elongated upper jaw.