tentorium

Early 19th century: from Latin tentorium, literally ‘tent’.

tentorium (plural tentoria or tentoriums)

1. The framework of internal supports (a false endoskeleton) within an arthropod head, formed by ingrowths of the exoskeleton called apophyses.
   • 1906, Milett T. Thompson, Alimentary Canal of the Mosquito: (Anopheles Punctipennis):

     In the female of Culex the tentoria arise in front of the border of the occipital foramen and ascend at an angle of twenty-five degrees with the floor of the head.

2. (anatomy) The tentorium cerebelli, an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.
   • 1961, Progress in Neurology and Psychiatry, page 345:

     Four dogs with intact tentoriums survived 6 weeks and 8 with sectioned tentoriums survived the same period of time.

• tentorial

From tendō (“to stretch out, to spread out”) +‎ -tōrium (suffix forming nouns denoting places or instruments).

tentōrium n (genitive tentōriī or tentōrī); second declension

1. tent

   Synonym: tabernaculum

Second-declension noun (neuter).

¹Found in older Latin (until the Augustan Age).

• “tentorium”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “tentorium”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• tentorium in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• tentorium in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• “tentorium”, in Harry Thurston Peck, editor (1898), Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers