The Fourth Infinitive -minen

The fourth infinitive, ending in -minen, is the one that turns a verb into a genuine, freestanding noun — "the act of X-ing." Where the third infinitive always leans on another verb (menen syömään), the -minen form stands entirely on its own: uiminen on hauskaa ("swimming is fun"), with uiminen doing exactly the job a noun does. This is the closest Finnish equivalent to the English gerund, and it is the tool you use whenever you want to name an activity rather than perform it.

Forming -minen

Add -minen to the strong vowel stem — the same stem the third infinitive uses. Harmony does not affect -minen itself (it is always spelled -minen, with those vowels), but it will matter as soon as you add case endings.

It declines like a -nen noun

Here is the point that catches everyone: -minen is not frozen. It inflects exactly like ordinary -nen nouns such as nainen ("woman") or hevonen ("horse"), whose stem swaps -nen for -se-. So tekeminen has the inflectional stem tekemise-, and every case is built on that.

Compare nainen → naisen → naista → naiseen and you will see it is the very same pattern; the full behaviour of these words is on the -nen words page. Because it is a real noun, -minen can also take the plural and even possessive suffixes (minun uimiseni "my swimming").

As a subject: naming the activity

The most common use is as the subject of a comment, exactly like the English "Swimming is good for you."

Governed in a case

Many verbs and expressions demand a particular case, and -minen obediently inflects to fit. After pitää jostakin ("like something") or nauttia jostakin ("enjoy") it goes into the elative -misesta; as a plain object it goes into the partitive -mistä.

There is also a very useful idiom: olla + partitive -mistä to mean "have (something) to do." Minulla on tekemistä = "I have things to do." Colloquially you will even hear the nominative used as a soft obligation, nyt on lähteminen ("now it's time to go") (colloquial / regional) — recognise it, but the standard phrasing is nyt on lähdettävä or nyt täytyy lähteä.

-minen vs. the -ma- infinitive

Keep the two -m- forms in their lanes. The -minen noun names an activity and can stand alone; the -ma- third infinitive cannot be a free subject and only appears governed by another verb. You can say uiminen on hauskaa, but not *uimassa on hauskaa.

That second sentence shows both forms side by side: uimassa (the third infinitive, governed by käyn) and uiminen (the fourth infinitive, standing as a noun subject). See the nominalization page for how -minen competes with other action nouns like -nti and -us.

English speakers overreach with -minen

Because English uses "-ing" everywhere — "I want swimming"? No: "I want to swim" — learners over-apply -minen. After modal and desire verbs (haluta, osata, voida, saada) Finnish wants the first infinitive, and after motion verbs the third. -minen is only for when the activity is genuinely a noun. The rule of thumb: if you could replace the English "-ing" word with "the act of X-ing" and the sentence still makes sense (the act of swimming is fun), Finnish uses -minen; if you could not (I want the act of swimming), it does not.

Common Mistakes

Key Takeaways

• -minen turns any verb into a full noun ("the act of X-ing"), built on the strong stem: puhuminen, tekeminen, uiminen.
• It declines like a -nen noun, stem in -mise-: tekemisen, tekemistä, tekemiseen, tekemisessä.
• Use it when the activity is a noun (subject, object, after pitää/nauttia), but switch to the first or third infinitive after modal and motion verbs.
• The idiom olla + -mistä ("have to do") and the fixed phrase ei ole tekemistä ("has nothing to do with") are worth memorising whole.