Questions & Answers about Tämä vaatimus on vaikea.
How does the word vaatimus fit into this lesson's topic of verb-to-noun derivation?
Vaatimus (requirement) is derived from the verb vaatia (to demand, to require). It uses the suffix -mus, which is a very common variation of the -us suffix you are learning. It attaches to the verb stem to create a noun that represents the result of the verb's action. Other common examples are tutkimus (research) and sopimus (agreement).
Could I use vaatimus to mean "the act of demanding"?
Usually, no. Suffixes like -mus, -us, and -os typically describe the result of the action or the specific thing produced (a requirement). If you want to talk about the ongoing action or process of demanding, you would use the -minen noun form instead: vaatiminen (the demanding).
What is the stem for vaatimus when adding other case endings?
Nouns ending in -mus change the exact same way as the -us nouns you are learning. To find the inflectional stem, change the final -s to -kse-. This makes the stem vaatimukse-. For example, "in the requirement" is vaatimuksessa. (Note that the partitive case adds -ta directly to the basic word without the -kse-: vaatimusta).
As a refresher, why is in the nominative case instead of the partitive case ()?