eines

Eines is the genitive singular form of the German numeral eins (one). It is not used as a stand-alone determiner in contemporary speech, but occurs in a small class of fixed phrases and literary constructions.

The most common use is in time expressions such as Eines Tages ("one day") and Eines Morgens ("one morning"), where the phrase means a non-specific point in time. Examples: Eines Tages beschloss sie, umzuziehen. Eines Morgens klingelte das Telefon. In these phrases, overall meaning is narrative rather than numerical.

Grammatical note: "eines" is the genitive form of "eins"; in these expressions it functions as a historical or stylistic marker rather than a count noun. In everyday language, speakers typically avoid such forms and use alternatives like an einem Tag or an einem Morgen, depending on the context and register.

Etymology: from German eins, which itself comes from Proto-Germanic *ainaz; cognate with English "one." The genitive "eines" reflects the old Germanic system of numeral declension and its retention in specific fixed expressions.

See also: Eins, Einer, Eines Tages.