From Latin fastigium.

• IPA^(key): /fæsˈtɪd͡ʒ.i.əm/

fastigium (plural fastigia)

1. An apex or summit; culmination.
2. (architecture) A pediment or gable end.
3. (pathology) The most intense phase of a disease, especially a fever.
   • 1871, C[arl Reinhold] A[ugust] Wunderlich, “Fundamental Principles”, in W. Bathurst Woodman, transl., On the Temperature in Diseases: A Manual of Medical Thermometry. [...] Translated from the Second German Edition (New Sydenham Society Publications; XLIX), London: The New Sydenham Society, →OCLC, § 32, page 14:

     [W]e find that the duration and succession of the febrile phenomena constitute five principal groups. […] 2. Fevers which are essentially continuous in their course (continued fevers), which exhibit but slight daily differences of temperature during their fastigium or acme, and defervesce rapidly (by crisis).

From Proto-Italic *farstjagjom, from Proto-Indo-European *bʰérstis, from *bʰers- (“tip”). Compare Middle Irish brostaim (“I goad, spur”), English bristle, Polish barszcz (“hogweed”).

• (Classical Latin) IPA^(key): /fasˈtiː.ɡi.um/, [fäs̠ˈt̪iːɡiʊ̃ˑ]
• (modern Italianate Ecclesiastical) IPA^(key): /fasˈti.d͡ʒi.um/, [fäsˈt̪iːd͡ʒium]

fastīgium n (genitive fastīgiī or fastīgī); second declension

1. peak, summit, top

   Synonyms: cacūmen, vertex, apex, culmen, summitās

   Antonym: fundus

2. extreme part, extremity of a thing

   Synonym: extrēmitās

3. slope, declivity, descent
4. gable
5. sharp point
6. highlight (of a story or poem)

Second-declension noun (neuter).

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

• fastīgō

• French: faîte (partially)
• Italian: fastigio
• Spanish: hastial
• → Portuguese: fastígio
• Sicilian: fastigiu
• → Spanish: fastigio

• “fastigium”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “fastigium”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• fastigium 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)
• fastigium in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• “fastigium”, in Harry Thurston Peck, editor (1898), Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers
• “fastigium”, in William Smith et al., editor (1890), A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin