pleon

Etymology
Borrowed from, from , present participle of ; from the fact that it bears the swimming limbs. Alternatively, perhaps in the sense of being longer or extended.

Noun

 * 1)  the abdomen of a crustacean

Derived terms

 * pleonal
 * pleopod

Etymology
Presumably from, but ultimate origin unknown. The OED comments "perhaps ult. borrowed from a non-Germanic language, although this would be unusual for a strong verb."

Verb

 * 1)  to endanger, risk