ceremoniassa
Ceremoniassa is often encountered as a form in Finnish writing, but it is not the standard inessive form for the noun meaning ceremony. The canonical Finnish inessive singular of the noun is seremoniassa, which translates to “in the ceremony” or “during the ceremony.” The form ceremoniassa is generally considered a misspelling or nonstandard variant. Finnish uses the inessive suffix -ssa/-ssä to indicate location or time within something, and in this case the correct stem is seremoni- from seremoni(a).
In usage, seremoniassa denotes being inside or participating in a ceremony, or referring to events occurring
Etymologically, seremoniassa derives from the noun seremonia, borrowed into Finnish from Latin ceremōnia via other European
See also: seremonia, inessive case, Finnish noun inflection, seremonia (etymology).