from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The rearmost segment of the body of certain arthropods.
- n. An extension of this segment, such as the middle lobe of the tail fan of a lobster or the stinger of a scorpion.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The part of an arthropod posterior to the last segment.
from the GNU version of the Collaborative International Dictionary of English
- n. The terminal joint or movable piece at the end of the abdomen of Crustacea and other articulates. See thoracostraca.
from The Century Dictionary and Cyclopedia
- n. In zoology, the last segment, or an azygous appendage of the last segment, or the median axis of the last segment, whether in one piece or more, of certain crustaceans and arachmidans, as the middle flipper of a lobster's tail-fin, the long sharp tail of a horseshoe-crab, and the sting of a scorpion.
Greek, limit.(American Heritage® Dictionary of the English Language, Fourth Edition)
Ancient Greek a boundary, limit. (Wiktionary)