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Questions & Answers about Tämä on viides päivä.
What is the role of Tämä?
Tämä is the proximal demonstrative pronoun “this,” serving as the subject (equivalent to English “this”).
What is on in this sentence?
on is the third-person singular present of olla (“to be”). Finnish does not drop the verb “to be” in full sentences, so you need on to link tämä and viides päivä.
Why is viides päivä in the nominative case?
Because olla requires nominative-case complements to express identity (predicate nominative). Both viides (fifth) and päivä (day) are in nominative singular.
Why isn’t there a word for “the” in Finnish?
Finnish has no separate definite or indefinite articles. Definiteness is understood from context or by demonstratives like tämä. So “the fifth day” is just viides päivä when you already know which day.
How do you form and inflect ordinal numbers like viides?
Most ordinals are formed by adding -s to the cardinal (e.g. kolme → kolmas). Some are irregular: viisi → viides. Ordinals behave like adjectives, so they agree in case and number with their noun: nominative viides päivä, genitive viidennen päivän, partitive viidettä päivää, etc.
Why would I sometimes see viidentenä päivänä instead of viides päivä?
viidentenä päivänä uses the essive case (-na/-nä on päivä) to express “on the fifth day” as a time adverbial. In your original sentence, you’re simply labeling the day (“This is the fifth day”), so you use the nominative viides päivä.
Can I drop on and just say Tämä viides päivä?
No. In Finnish, you need the verb olla (“to be”) in present tense to form a complete sentence. Without on, Tämä viides päivä is only a noun phrase (“this fifth day”), not a full statement.