"statement in passing," a judge's expression of opinion not regarded as binding or decisive, Latin, literally "something said incidentally;" from obiter "by the way" + dictum in the legal sense "a judge's expression of opinion which is not the formal resolution of a case or determination of the court."
Obiter dicta, legal dicta ... uttered by the way (obiter), not upon the point or question pending, as if turning aside for the time from the main topic of the case to collateral subjects. [Century Dictionary]
Latin obiter is from ob "in front of, toward" (see ob-) + iter "journey" (from PIE root *ei- "to go"). Klein's sources, however, say it is ob with the suffix -iter on analogy of circiter "about" from circa. Also see obituary.
1890, from French fin de siècle "end of century," phrase used as an adjective. At the time it meant "modern;" now it means "from the 1890s." "App. first in title of a comedy, Paris fin de siècle, produced at the Gymnase, Feb. 1890" [Weekley]. French siècle "century, age" is from Latin saeculum "age, span of time, generation" (see secular).
No proof is needed of the extreme silliness of the term. Only the brain of a child or of a savage could form the clumsy idea that the century is a kind of living being, born like a beast or a man, passing through all the stages of existence, gradually ageing and declining after blooming childhood, joyous youth, and vigorous maturity, to die with the expiration of the hundredth year, after being afflicted in its last decade with all the infirmities of mournful senility. [Max Nordau, "Degeneration," English translation, 1895]