User:Rua/Finnish declension

This article describes the declension of nominals (nouns, adjectives and pronouns) in Finnish. For a general overview of Finnish grammar, see the Finnish grammar article.

Case endings
The following endings are used for the cases. Some cases allow more than one ending; this is discussed below. The letters S and W indicate strong and weak grade of consonant gradation, explained further below.

For nouns with front-vowel harmony, all a in endings should be replaced by ä.

Consonant gradation
Many nouns display consonant gradation. However, depending on declension type, gradation applies differently in different cases. There are two different gradation patterns: final and penultimate gradation.

Final gradation affects the last consonant(s) of the stem, and applies to all nouns that have gradation. In the table above, forms that use the strong grade of the last consonant(s) have "S", while the forms that use the weak grade have "W". All consonant stem nouns show final gradation, but certain types of consonant stem nouns also show patterns of gradation that are rare or nonexistent elsewhere, such as t > - (ohut ~ ohuen) or s > h/- (mies ~ miehen, vieras ~ vieraan).

Penultimate gradation affects the penultimate consonant or consonant cluster of the stem, and applies only to consonant stem nouns, which have a nominative singular ending in a consonant or in -eˣ. In these nouns, the penultimate consonant(s) are in the weak grade in the nominative singular, or in any form in which the ending is attached directly to the final consonant (the partitive singular ending -ta, and the genitive plural ending -ten). The strong grade appears in all other forms, in which the final consonant is followed by a vowel (the final consonant may undergo gradation itself, or disappear altogether). For example:
 * kuningas ~ partitive singular kuningasta, but genitive singular kuninkaan, where an additional vowel is inserted and s disappears.

Assibilation
Many older nouns with single t as the final consonant undergo a change known as assibilation. Assibilation is the change of ti/di to si, and of hti/hdi to ksi. It often occurs in the nominative singular, and in most of the plural forms. Some examples:
 * Nominative singular vesi ("water"), genitive singular veden, essive singular vetenä, inessive plural vesissä.
 * Nominative singular kynsi ("nail"), genitive singular kynnen, essive singular kyntenä, inessive plural kynsissä.
 * Nominative singular yksi ("one"), genitive singular yhden, essive singular yhtenä, inessive plural yksissä.

This change certainly does not affect all nominals. I-stem nominals (which includes all recent loanwords) are normally exempt, but there are also some old i/e nominals which do not show the change. For example:
 * Nominative singular tauti ("disease"), genitive singular taudin, essive singular tautina, inessive plural taudeilla.
 * Nominative singular lahti ("bay"), genitive singular lahden, essive singular lahtena, inessive plural lahdissa.

Notice that the change overrides consonant gradation: both the strong (nominative singular) and weak (inessive plural) grades are affected indiscriminately.

One group of consonant-stem nouns shows assibilation in the nominative singular, but the final -i itself has disappeared. In the plural forms, -si- has been replaced by -ksi-. For example:
 * Nominative singular ahtaus ("tightness"), genitive singular ahtauden, essive singular ahtautena, inessive plural ahtauksissa.

Case formation
Many forms can be predicted regularly from other forms, by using the same basic stem but attaching another ending. The forms that are used to derive the others from are called principal parts. The forms that can be used to form other parts are listed here, along with the forms that can be derived from them:
 * Genitive singular (inessive, elative, adessive, ablative, allative, translative, abessive singular, nominative/accusative plural). If the nominal has gradation, this stem always has weak final gradation.
 * The essive singular has the same stem, but with strong final gradation.
 * Inessive plural (elative, adessive, ablative, allative, translative, instructive, abessive plural). If the nominal has gradation, this stem always has weak final gradation.
 * The essive and comitative plural have the same stem, but with strong final gradation.

The formation of the remaining cases (nominative, partitive and illative singular, and genitive, partitive and illative plural) is more unpredictable, and is described in more detail below.

Nominative singular
The nominative singular normally has no ending. In most nominals, it ends in a vowel of some sort, which is not an ending but part of the stem itself. There are also many nominals where the nominative singular ends in a consonant. The nominative singular may be identical to the stem of the essive singular, but it may also be different. For example, i/e nominals have a stem ending in -e-, but this becomes -i in the nominative singular: järvi ("lake"), essive singular järvenä.

Consonant-stem nominals have no ending in the nominative singular at all, if the base stem (without final vowel) has two or more syllables. Final consonant clusters are simplified when this happens, as Finnish does not allow a word to end in more than one consonant. For example: kytkin ("switch"), essive singular kytkimenä; vastaus ("answer"), essive singular vastauksena. Consonant-stem nominals may also undergo other irregular changes in the final consonant.

Partitive singular
The ending of the partitive singular is normally -a/ä, attached to the essive singular stem (strong final grade). The ending -ta/tä is used:
 * After a long vowel or diphthong: maata, koita, vapaata.
 * After a sequence of two vowels, if the second vowel is not a/ä (to prevent a sequence of three vowels): valtiota, aaloeta.
 * If the second vowel is a/ä, either ending is possible: korkeaa/korkeata, ainoaa/ainoata.

For consonant-stem nominals, the ending is always -ta/tä, and is attached directly to the basic stem with no preceding vowel:
 * sisar > sisarta
 * vastaus > vastausta
 * nainen > naista

If the nominative singular of a consonant stem nominal has a final vowel, it is removed, and any preceding consonant cluster is simplified or changed in other ways: When the final consonant is -m, both endings are possible: toimi > tointa/toimea.
 * uni > unta
 * käsi > kättä (assibilation; compare essive singular kätenä)
 * lapsi > lasta
 * kaksi > kahta (assibilation; compare essive singular kahtena)

In nouns ending in -eˣ, gemination occurs:
 * hameˣ > ''hametta

In two nouns, the partitive singular has the back-vowel variant -ta while all other forms have the front vowel ä in the endings:
 * meri, essive singular merenä, but partitive singular merta
 * veri, essive singular verenä, but partitive singular verta

Illative singular and plural
The illative singular is most commonly formed by taking the essive singular stem (strong final grade), and adding a copy of the final vowel (indicated by "V") plus -n.

The illative singular has two alternative forms, -hVn and -seen, which are used whenever the stem ends with a long vowel or diphthong. The rules for when to use which are not so straightforward. Some general indications:
 * Nominals with stem ending in a diphthong always use -hVn: koihin, torstaihin, tiehen.
 * Nominals with one syllable ending in a long vowel always use -hVn: maahan.
 * Nominals with stem ending in a long back vowel (aa, oo, uu) prefer -seen: vapaaseen, tienooseen, leikkuuseen.
 * Nominals with stem ending in a long front or neutral vowel (öö, yy, ee) prefer -hVn but allow -seen: fileehen/fileeseen, miljööhön/miljööseen, menyyhyn/menyyseen. These are primarily loanwords.
 * Consonant-stem nominals with a stem ending in a long vowel (that is, those that lose their final consonant) always use -seen: vieras > vieraaseen, kuollut > kuolleeseen (genitive kuolleen), hameˣ > hameeseen.

The illative plural is formed just like the singular, but from the essive plural stem (strong final grade). As the plural marker -i- is always placed before the ending, the copied vowel is always -i-. Because the essive plural stem often ends in a diphthong, the -ihin variant is much more frequent. With nominals of three or more syllables and a double consonant in the strong grade, both grades can be used in the illative plural:
 * laatikko > laatikkoihin/laatikoihin
 * solakka > solakkoihin/solakoihin

The plural counterpart of -seen is -isiin. It is used whenever the singular uses -seen, but the -ihin form is usually allowed as well, as an alternative. The -isiin ending is also used when the singular stem ends in two vowels that do not form a diphthong:
 * korkea > illative singular korkeaan, but illative plural korkeisiin/korkeihin (essive plural korkeina)

Genitive and partitive plural
The genitive plural is probably the most difficult case to form, as there are several different ways to form it, and no straightforward rules that allow one to reliably decide which to use. The formation of the partitive plural is mostly parallel to the genitive plural, so that knowing one will generally allow the other to be predicted.

A distinction is made between endings that attach to a vowel and those that attach to a consonant. There is also a distinction between "light" endings, where the penultimate syllable ends in a short vowel, and "heavy" endings, where the penultimate syllable ends in a long vowel, diphthong or consonant. This can be summarised as follows:

The endings -iden and -itten are alternatives of each other. If one of them is allowed, the other can always be used as well.

The endings are attached to a variety of stems:
 * The genitive plural ending -ten occurs exclusively with consonant stem nouns, and is attached to the final consonant, like in the partitive singular.
 * The other heavy endings attach to the inessive plural (weak final grade) stem.
 * The light endings attach to the essive plural (strong final grade) stem.

Declensional classes

 * nouns in -u, -y, -o, -ö, -e (1/valo, 2/palvelu, 3/valtio, 4/laatikko, 8/nalle)
 * i-stems (5/risti, 6/paperi)
 * i/e-stems (7/ovi)
 * a/ä-stems that with o/ö in the plural (9/kala, 11/omena, 12/kulkija, 13/katiska, 14/solakka)
 * a/ä-stems that drop the final vowel in the plural (10/koira, 11/omena, 15/korkea, 16/vanhempi)
 * Long vowel/diphthong stems (17/vapaa, 18/maa, 19/suo, 20/filee)