pleon
noun
ple·on
ˈplēˌän
plural -s
1
: the abdomen of a crustacean
2
: the telson of a horseshoe crab
pleonal adjective
-ēənᵊl
or pleonic
(ˈ)plē¦änik
Word History
Etymology
New Latin, from Greek pleōn, present participle of plein to sail; from the fact that it bears the swimming limbs