noun thread·fin \-ˌfin\

Definition of threadfin

  1. :  any of various bony fishes (family Polynemidae, especially genus Polydactylus) having elongated filamentous rays on the pectoral fin; also :  a fish (such as Dorosoma pretense of the herring family) having usually one similar ray extending from a fin

Circa 1890

First Known Use of threadfin

circa 1890

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