caerimonia

Latin

Uncertain.

The word formally matches Sanskrit कर्मन् (kárman, “action, deed; karma”), as if both were from Proto-Indo-European *kʷermon-, itself an abstract noun formed from Proto-Indo-European *kʷer- (“to do, make”).
According to de Vaan, it's a derivation from the unattested adjective *caerus +‎ -mōnia also found as the second part of the compound sincērus (“whole, sound”); however, if so, the expected outcome of the latter would be *sincīrus.
Roman folk etymology held this word as coming from the name of the city of Caere.

(Classical Latin) IPA^(key): /kae̯.riˈmoː.ni.a/, [käe̯rɪˈmoːniä]
(modern Italianate Ecclesiastical) IPA^(key): /t͡ʃe.riˈmo.ni.a/, [t͡ʃeriˈmɔːniä]

caerimōnia f (genitive caerimōniae); first declension

“caerimonia”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
“caerimonia”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
caerimonia 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)
caerimonia in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
Carl Meißner, Henry William Auden (1894) Latin Phrase-Book‎^[1], London: Macmillan and Co.
- to invoke an irrevocable curse on the profanation of sacred rites: violatas caerimonias inexpiabili religione sancire (Tusc. 1. 12. 27)
De Vaan, Michiel (2008) Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill, →ISBN, page 81