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tridacna

noun
tri·​dac·​na | \trə̇ˈdaknə\

Definition of tridacna 

1 capitalized : a genus of marine bivalves (family Tridacnidae) having no anterior adductor muscle and an equivalve shell the valves of which are very thick and heavy and strongly plicated at the margin — see giant clam

2 plural -s : any mollusk of the genus Tridacna : giant clam

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History and Etymology for tridacna

New Latin, from Latin, an oyster, from Greek tridaknos eaten at three bites, from tri- three + -daknos (from daknein to bite)

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