Learn Finnish: Kokous kesti vain hetkisen. - The meeting lasted only a brief moment.

The root word is hetki (moment). By adding the -nen suffix, we get the diminutive hetkinen (a brief moment). Because it expresses how long the meeting lasted, it takes the accusative case, changing the -nen ending to -sen.

Why is hetkisen in the accusative case (ending in -n) instead of the partitive?

In Finnish, a specific, completed amount of time (duration) acts like a total object, so it takes the accusative case. Since hetkinen is a singular word, its accusative form looks identical to the genitive (hetkisen). If the sentence were negative (The meeting didn't last a moment), it would take the partitive case (hetkistä).

Does using the diminutive hetkisen instead of the standard hetken change the meaning?

Yes, it adds a descriptive nuance. While hetken just means 'for a moment', adding the -nen suffix creates hetkisen, which emphasizes that the moment was particularly brief. It makes the statement feel a bit softer and more expressive.

Why does the verb kestää (to last) trigger object-like cases for time expressions?