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macrocystis

noun
mac·​ro·​cys·​tis | \ ˌmakrōˈsistə̇s\

Definition of macrocystis

1 capitalized : a genus of brown algae (family Laminariaceae) that are often very large and consist of a slender stipe with pinnate fronds and floats — see giant kelp
2 plural macrocystis : any plant of the genus Macrocystis

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History and Etymology for macrocystis

New Latin, from macr- + -cystis

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