This article describes the usage and the formation of the illative plural, aka monikon illatiivi. In many Finnish courses currently, the illative will be referred to as the S-mihin form. Thus, this page deals with the plural S-mihin form. I have a separate pages on the singular S-mihin form.

The illative is used to express a movement towards or into a place (e.g. menen kirkkoon). The plural is also used in phrases like Tutustun suomalaisiin ihmisiin (I get to know Finnish people) and Olen tottunut pimeisiin syksyihin (I’ve gotten used to dark autumns). These are refered to as “rections”, ie. the verb requires the illative case to be used.

1. Use of the Plural Illative (mihin)

1.1. When saying TO or INTO

The illative has several different-looking endings (see below), but the most common usage is when expressing a movement into something or towards something or somewhere. In English you usually use “to” or “into”. However, Finnish and English don’t match up when it comes to English prepositions such as “in” and “to”. Don’t rely on English too much! Translating directly will create issues.

The plural illative is used when the thing or location is plural. Thus, “Laitan kirjat kaappiin” (I put the books in the cupboard) is singular, and “Laitan kirjat kaappeihin” (I put the books in the cupboards) is plural.

There can be some confusion with the allative, which also is translated as “to” in some cases. In general, the illative can be translated as “into”, while the allative is translated as “onto”. However, both will often be translated as “to”. Again, don’t rely on English!

1.2. When using certain verbs

Finnish has this concept of “rections”: most words will require other words that they get combined with to appear in a certain case. There are several verbs that require mihin. Some examples are tutustua (to get to know), rakastua (to fall in love) and tottua (to get used to). You can learn more about verb rections here, where section 3.1 focuses on rections with the illative case.

2. The Formation of the Plural Illative Case

The illative is one of the six location cases. It’s different from the other location cases for at least two reasons. First, its ending is added to the strong form of the word (learn more about consonant gradation for wordtype A here and for wordtype B here).

Second, the plural illative has several different endings, depending on the type of word you’re dealing with (-iin, -ihin, -isiin). All these endings have in common that they have the plural marker -i-.

2.1. Words ending in -u/-y, -o/-ö: add -i- + hin

Note that words of more than two syllables often have their own rules. For words ending in -u/y/o/ö, the only difference is that the plural illative can be both strong and weak in words that end in -kko/kkö (e.g. laatikko can be inflected both as laatikkoihin and laatikoihin).

2.2. Words ending in -a/ä

2.2.1. Two-syllable words ending in -ä: replace the -ä with -iin

2.2.2. Two-syllable words ending in -a: kissa-words

I call the two groups of words ending in -a by the names “kissa-words” and “koira-words”. These two words are easy to remember and each belongs to a different group of words ending in -a. If you can remember “kissa – kissoihin” and “koira – koiriin” and apply that rule to other, similar words, you’re on your way to mastering the plural S-mihin form!

Kissa-words are words of two syllables. Their final letter is -a. In the first syllable, you will have either -e-, -i- or -a-. In other words, the vowels of these words can look like:

• a…a (kana, maksa, sana, marja)
• e…a (herra, tela, teema, leija)
• i…a (kissa, tina, hinta, silta)

When you inflect these words in the plural illative, you will replace the final -a with -oihin.

2.2.3. Two-syllable words ending in -a: koira-words

Koira-words are also words of two syllables. Their final letter is also -a. They differ when it comes to the first syllable: for koira-words you will have either –o- or -u- in the first syllable. In other words, the vowels of these words can look like:

• o…a (koira, konna, honda, nokka)
• u…a (kukka, sukka, suora, juoma)

For koira-words, you will replace the final -a with -iin.

2.2.4. Words ending in -ja/jä: two groups

There are two groups of words ending in -ja/jä, which match up perfectly with the groups in the plural partitive. For these words, the rule is the same for short and long words. The rule:

1. If there’s an -i- in front of the -ja/jä (e.g. opiskelija), the plural illative’s marker will be -oihin (opiskelijoihin).
2. If there is another vowel in front of the -ja/jä (e.g. opettaja), the plural illatives’s marker will be –iin (opettajiin).

2.2.5. Long words ending in -a/ä

Words of more than two syllables partially have their own rules. I’m hiding this section because it’s a good idea to first learn the rules for short words, before adding long words into the mix. After all, Finnish has an abundance of two-syllables words, so you will need those rules most often.

2.3. Words ending in -i

Words ending in -i are once again divided into several groups. There are new words, which are often loanwords. There are also older, more Finnish words, which are inflected differently.

2.3.1. New words ending in -i: remove -i and add -eihin

There are some strategies for determining if a words is new. First, if the word sounds similar to an English, Swedish or Russian word you knw, it’s probably a new word. Second, imagine the Stone Age and ask yourself if the thing existed in Finland in that day and age. Third,  if the word have three or more syllables, it’s also likely a new word. Original Finnish words are mainly two-syllable words. None of these strategies will help you will all words ending in -i, but it’s a useful concept nevertheless.

For this particular group, the number of syllables in the word has no effect on the inflection.

2.3.2. Old words ending in -i: will end in -iin

These old words often refer to things that have been around for centuries. Two very common groups are words related Finnish nature (lake, mushroom, stone, leaf, etc.) and bodyparts (finger, knee, cheek, etc.).

2.3.3. Old words ending in -si: will retain their -si-, and end in –iin

Again, many of these are nature words and bodyparts. The only difference is that they end in -si.

2.4. Words ending in -e: add -isiin

For most words ending in -e the follow hold true: In the singular illative, words ending in -e will get a -ee-, to which we add -seen (e.g. huone-e-seen). In the plural, we replace one -e- from the stem with the plural marker -i-, and add -siin (e.g. huone-i-siin). Remember to pay attention to consonant gradation! These words belong to wordtype B, so the basic form is weak and the S-mihin form is strong. Please note that technically these words have a second, very rarely used plural S-mihin case ending: -ihin (e.g. huoneihin and kirjeihin).

Some words ending in -e don’t belong to the above category:

1. Recent loanwords (e.g. deadline becomes deadlineihin) – See section 6.1.
2. Loanwords ending in two e‘s (e.g. filee becomes fileihin or fileisiin) – See section 8.
3. Some colloquial words (e.g. bisse becomes bisseihin) – See section 6.3.
4. Some old Finnish words (e.g. kolme becomes kolmiin). – See section 6.2.

2.5. Words ending in -nen: replace the -nen with -siin

2.6. One syllable words ending in two vowels: replace a vowel with -ihin

Words of one syllable can have a long vowel (e.g. maa, suu) or a diphthong (e.g. työ, suo). For all of these words, you will remove a vowel of the word and add -ihin. However, which vowel is removed depends on the word in question.

1. For words ending in a long vowel (e.g. maa), you will remove one vowel and add -ihin (maihin).
2. For words with a diphtong (e.g. työ), you will remove the first vowel (e.g. töihin with the -y- removed).
3. For words ending in an -i (e.g. voi), you will remove the -i when adding -ihin, so you have only a single -i- (voihin).

2.7. Words ending in a long vowel: replace the last vowel with -isiin

When inflecting words ending in two of the same vowel, the singular illative marker is -seen (e.g. vapaaseen). In the plural, we replace one of the singular stem’s vowels with the plural marker -i, to which we add -siin (e.g. vapa-i-siin). While technically, these words can also have the -ihin ending (e.g. vapaihin), it’s very rare.

Note that this group only contains words that are not compounds. For example, the word elokuu (August) consists of elo+kuu, so it is inflected as the one-syllable words in seciont 2.9.

2.8. Words ending in -ea/eä: two groups

Adjectives ending in -ea/eä, can get both -isiin and -eihin, though -isiin is much more common. Nouns ending in -ea/eä will have their final -a/ä replaced with -oihin.

2.9. Words ending in two different vowels

For words ending in two different vowels other than -ea/eä (e.g. radio), you will simply add -ihin to their end without touching the final two vowels.

2.10. Words ending in a consonant

2.10.1. Words ending in -as: replace -as with -ai- and add -siin

In the singular, the vowel stem ends in a double vowel to which we add the singular illative marker -seen (e.g. rakkaaseen). In the plural, we replace one of the singular stem’s vowels with the plural marker -i, to which we add -siin (e.g. rikka-i-siin). While technically, these words can also have the -ihin ending (e.g. rakkaihin), it’s very rare.

Words ending in -as/äs belong to wordtype B, so they will have the weak grade in their basic form (e.g. rakas, opas) and the strong grade in the illative (e.g. rakkaisiin, oppaisiin). Read more about words ending in -as here.

2.10.2. Words ending in -is: two groups

For words ending in -is, we have two groups. Read more about the two types here.

1. Kallis: Words like kallis are older Finnish words. In the singular, the illative case ending is -seen (e.g. kalliiseen). In the plural, they get the same -ii- stem, to which we add -siin (e.g. kallii-siin). While technically, these words can also have the -ihin ending (e.g. kalliihin), it’s very rare.
2. Roskis: Words like roskis are usually spoken language words. Their singular stem is -ikse-, while the plural stem is -iksi-. For the illative, we add -in to the plural stem. Read more about spoken languages words ending in -is here.

2.10.3. Words ending in -us/-os: replace the -s with -ksiin

In the singular forms, words ending in -us/ys often belong to one of two types: they either get -ude- in their stem, or -ukse-. The plural forms don’t make that distinction: you will use -uksiin for both in the plural S-mihin form. Read more about the singular forms here.

2.10.4. Words ending in -es: replace the -s with -ksiin

Words ending in -es belong to the same inflection types as us>ukse words. In the singular, their stem ends in -ekse-. In the plural, the final -e- of the stem gets replaced by the plural marker -i- to which we add the illative’s -in ending.

Note that there are at least two notable exceptions. The first is kirves (stem: kirvee-), so the singular illative is kirveeseen and the plural kirveisiin. The other is mies (stem: miehe-), so the singular illative is mieheen and the plural miehiin.

2.10.5. Words ending in -ton: replace with -ttomi- and add -in

Read more about words ending in -ton/tön here. The singular vowel stem for these words is -ttoma-. In the plural, you remove the singular stem’s -a-, which gives you the plural stem -ttomi-, to which you add -in. Rather than going through all these steps, it might just be easier to thing of it as removing the -ton/tön and adding -ttomiin/ttömiin.

2.10.6. Words ending in –in: replace with -imi- and add –in

In the singular, the vowel stem ends in -ime- (e.g. puhelime-). In the plural, we replace one of the singular stem’s vowels with the plural marker -i, to which we add -in (e.g. puhelim-i-in).

Read more about words ending in -in here. Words ending in -in belong to wordtype B, so they will have the weak grade in their basic form (e.g. keitin) and the strong grade in the illative (e.g. keittimiin).

2.10.7. Words ending in –ut: two groups

Words that end in -ut/yt can belong to two wordtypes. The smallest group of the two contains words such as olut, kevyt and lyhyt. In the singular, the stem of these words has the -t replaced by -e- (e.g. kevye-). In the plural, this final -e- will be replaced with the plural marker -i-, to which we add -siin (e.g. kevy-i-siin).

These words have a second possible plural illative ending: -ihin, which is very rare.

The much larger group is made up of NUT-participles such as väsynyt and tottunut. In the singular, the stem of these words has the -nut/nyt replaced by -nee- (e.g. väsynee-). In the plural, the final -e- will be replaced with the plural marker -i-, to which we add -siin (e.g. väsyne-i-siin).

2.10.8. Words ending in -tar/tär

Words ending in -tar/tär are rare, but at least tytär (daughter) is a common word.

In the singular, the stem of these words has the -tar/tär replaced by -ttare/ttäre- (e.g. tyttäre-). In the plural, the final -e- of the stem will be replaced with the plural marker -i-, to which we add -in (e.g. tyttär-i-in).

2.10.9. Loanwords ending in a consonant

For loanwords where the final letter is pronounced, you will add -eihin for the plural S-mihin form. The ones which end in an unvoiced consonant, you will usually use an apostrophy and -ihin.

3. Consonant Gradation in the Plural Illative

The plural illative will nearly always be strong, both for wordtype A and wordtype B.

I have a separate article on wordtype A.

While the plural S-mihin of short words in usually strong, long words ending in -a can have two versions: a weak and a strong version. This is true for words ending in -kka/kkä and -tta/ttä.

I have a separate article on wordtype B.

That concludes the article on the plural illative case!

Related posts:

The Illative Case (Mihin) – S-Mihin – Finnish Grammar Location Case Verb Rections – Rektiot Missä Mistä Mihin The Plural Forms in Finnish – Examples