swimmeret
noun
swim·mer·et ˌswi-mə-ˈret 
ˈswi-mə-ˌret
: one of a series of small unspecialized appendages under the abdomen of many crustaceans that are best developed in some decapods (such as a lobster) and usually function in locomotion or reproduction
Example Sentences
Recent Examples on the Web The kangaroo was a particular hit, but other animal builds in the kit include a leopard, mouse, boar, monkey—and a mantis shrimp, complete with leg-like swimmerets. 
Michelle Z. Donahue, Smithsonian, 26 Nov. 2019
Michelle Z. Donahue, Smithsonian, 26 Nov. 2019 Word History
First Known Use
1840, in the meaning defined above
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