from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The dorsal portion of a body segment of an arthropod.
from The Century Dictionary.
- noun The back, dorsum, or notum, especially of an arthropod.
- noun The tergal or dorsal sclerite of one of the rings or somites of an arthropod or articulate animal; a tergite.
- noun One of the two upper or dorsal plates of the shell in cirripeds. See cut under
from the GNU version of the Collaborative International Dictionary of English.
- noun The back of an animal.
- noun The dorsal piece of a somite of an articulate animal.
- noun One of the dorsal plates of the operculum of a cirriped.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun biology The
upperor dorsalsurface of an articulated animal such as an arthropod
from The American Heritage® Dictionary of the English Language, 4th Edition
From the Latin 'tergum', back + 'versus', past participle of 'vertare', to turn: to use evasions or ambiguities, equivocate; to change sides, defect, apostasise.
Sed nec inter tantos repertus est vel unus, qui, tanquam vecors ant timidus, sive post tergum alterius declinans, seipsum a tanta caede praetendit excusare.
 Bartholomeus Scheraeus, that famous poet laureate, and professor of Hebrew in Wittenberg: I had finished this work long since, but that inter alia dura et tristia quae misero mihi pene tergum fregerunt, (I use his own words) amongst many miseries which almost broke my back, συζυγία ob
Juvenis autem dextra pugionem super tergum tonsoris vibrans magna clamat voce [Arabic] i.e. caede sine timore.
‘Quod protenditur a limite Serrain urbis sitae ad mare Kolzum adusque viciniam Madian, et inde reflectendo per limitem tendentem in ortum urbis Hhegr, ad montem Tai trunseundo juxta tergum Yamamah ad mare Persicum, hoc totum ad Hhegiaz pertinet.’
Notum: the dorsal or upper part of a segment: = tergum.
The phrase _in tergum_ occurs twice elsewhere: ix. 764 -- meaning 'on the back'; and xi. 653 -- meaning 'backward'; and in x. 718 the uncertainty about the order of the lines makes it possible that _tergo decutit hastas_ was meant to refer to the boar, not to Mezentius.
Ille igitur tergum vertit, et in speculum ínspiciébat; hóc modó ad locum vénit ubi Medúsa dormiébat.
This is evasion (_tergiversatio_) for by desisting from what he had begun he seems to turn his back (_tergum vertere_).
Audouin distinguished a fixed number of hard chitinous parts, the dorsal tergum, the ventral sternum, the lateral "flanc" of three pieces, all to be recognised by their positions relative to one another.