plural noun Ac·ti·nop·te·ryg·ii \¦ak-tə-ˌnäp-tə-ˈri-jē-ˌī\

Definition of Actinopterygii

in many classifications

  1. :  a subclass or other division of Teleostomi comprising fishes having the projecting part of the paired fins supported only by dermal rays and being coextensive with the Teleostomi excluding the Choanichthyes


\¦ak-tə-ˌnäp-tə-ˈri-jē-əs\ adjective

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Origin and Etymology of actinopterygii

New Latin, from actin- + -pterygii (from Greek pteryg-, pteryx wing); akin to Greek pteron feather, wing — more at feather

First Known Use: 1896

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to cast off or become cast off

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