Capitolium

English Wikipedia has an article on:

Capitolium

Wikipedia

From Latin Capitōlium (“Capitoline Hill, its temples; similar citadels”), from the oblique stem of caput (“head”) + -ō (noun-forming suffix) or -ōlus (“-ole”, diminutive suffix) + -ium (suffix forming place names). Doublet of capitol and capitoul.

the Capitolium

1. (uncommon) Synonym of Capitoline Hill.

Capitolium (plural Capitolia)

1. (historical, uncommon) Synonym of capitol, similar citadels in ancient Italian and Roman towns.

From the oblique stem of caput (“head”) + -ō (noun-forming suffix) or -ōlus (“-ole”, diminutive suffix) + -ium (suffix forming place names). Compare capito and capitulum.

• (Classical Latin) IPA^(key): /ka.piˈtoː.li.um/,
• (modern Italianate Ecclesiastical) IPA^(key): /ka.piˈto.li.um/,

Capitōlium n sg (genitive Capitōliī or Capitōlī); second declension

1. The Capitoline Hill, one of the seven hills of Rome, particularly (historical) the Roman temples there in antiquity.

Second-declension noun (neuter), singular only.

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

• Capitolinus, Mons Capitolinus, Clivus Capitolinus; Mons Saturnius, Mons Tarpeius (historical)

• Inherited forms:
  • Old French: capitoile, capitolie
    • → Middle English: Capitolie
      • English: Capitol, capitol
  • Italian: Campidoglio
  • Old Occitan: capdolh
    • Auvergnat: Chaptuèlh
      • → French: Chapteuil
  • Sicilian: Capitugghiu
• Borrowings:
  • → English: Capitolium (learned)
  • → Portuguese: Capitólio (learned)
  • → Sicilian: Capitùliu (learned)
  • → Spanish: Capitolio (learned)

Capitōlium n sg (genitive Capitōliī or Capitōlī); second declension

1. (figurative) Any eternal thing.
2. (figurative) Any similar citadel in other towns.
3. (Medieval Latin, Ecclesiastical Latin) Any pagan temple.

Second-declension noun (neuter).

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

• Walther von Wartburg (1928–2002) “capitŏlium”, in Französisches Etymologisches Wörterbuch, volume 2: C Q K, page 265