Other variation in word stem

Variation -i : -e-

Words that end with i in nominative singular very often have e- in inflected forms, as in kivi : kiven (stone). However, new loanwords normally have an unchanged i-, as in filmi : filmin. Moreover, in many words, i is a derivational suffix and is preserved in inflection, as in koti : kodin (home), based on kota (hut).

Due to this stem variation, different forms of different words may coincide. Some forms of the words vuori : vuoren (mountain) and vuori : vuorin (lining) are shown in the next table.

This means that the illative plural of vuori : vuoren is the same as the illative singular of vuori : vuorin. Other case forms are similarly confusing, but the illative tends to confuse even native speakers. It is now permitted to inflect both of these specific words as vuori : vuoren, since language authorities regard the distinction as too difficult. However, this is not a general rule. For example, the words laki : lain (law) and laki : laen (top of hill) must be kept as separate.

Vowel changes before an i suffix

Some vowel changes take place at the end of a stem that ends with a vowel, when followed by a suffix that starts with i. One of the changes is that a final long vowel becomes short, e.g. aa changes to a. The suffixes that cause such changes are:

• the plural suffix i, e.g. maa : ma|i|ssa (country : in countries)
• the superlative suffix in : imma : impa, e.g. vapaa (free) → vapa|in : vapa|imma|n : vapa|impa|na (the most free : of the most free : as the most free)
• the past tense suffix i, e.g. saa|da : sa|i|n (to get : I got)
• the conditional mood suffix isi, e.g. i, e.g. jää|dä : jä|isi|n (to stay : I would stay)

The changes that may happen are:

1. Shortening of a long vowel, as described above. This includes changes like kaunis : kaunii|ssa : kauni|i|ssa, where the last form is plural—identical with the corresponding singular form, but analyzed differently.
2. Change of ii to e.
3. Loss of the first component of a diphthong ie, uo, yö.
4. Loss of the i in a diphthong that ends with i. This means that two successive i’s are not used, and it could also be described so that the latter i is omitted. It is however better to describe this as stem variation, especially since the suffix may consist of i alone.
5. Loss of short e. This relates to words that have e in the normal inflection stem and i in the dictionary form, e.g. suuri : suure- (large).
6. Change of i to e. This relates to words that otherwise have the i unchanged, e.g. lasi : lasin, filmi : filmin.
7. Loss of i.
8. Loss of a or ä after another vowel.
9. Loss of ä.
10. Change of ä to ö. This happens only for some 3-syllable nouns; it usually happens in them if the vowel of the 2nd syllable is i or y (e.g., kynttilä, päärynä, rähinä, tekijä).
11. Loss of a.
12. Change of a to o.

The changes do not always take place in all of the forms and contexts. The following table shows the basic rules for this. Each cell there shows an example; if there is no example in a cell, then the change does not apply.

The changes of a final A (the last four rows of the table) are subject to somewhat complicated rules, and even native speakers make mistakes with them. In two-syllable words, the basic rules are that in plural and past tense forms,

• -a is lost, if the first vowel is o or u (i.e., a labial vowel), e.g. sola : sol|i|ssa
• -a is changed to -o-, if the first vowel is a, e, or i, e.g. sala : salo|i|ssa, reuna : reuno|i|ssa
• -ä is always lost, e.g. kylä : kyl|i|ssä, määrä : määr|i|ssä

  There are some exceptions to these rules, e.g. suola : suolo|i|ssa (salt : in salts), which avoids clashes with the forms of the word suoli : suol|i|ssa (intestine : in intestines).

  In words longer than two syllables in the base form:

• In past tense forms of verbs, -A is always lost before the i, e.g. pitä|ä : pit|i.
• In plural forms of nouns, -A is mostly changed to -O- before the i, e.g. ikkuna : ikkuno|i|lla. However, -A is lost if it is
  • preceded by m, e.g. satama : satamissa (but in new loanwords, there are exceptions to this exception, e.g. dioraama : dioraamoissa)
  • preceded by v, e.g. kanava : kanavissa
  • preceded by a consonant
  • part of jA derivational suffix preceded by something else than a consonant and i, e.g. opettaja : opettajilla (but lukija : lukijoilla); but armeija : armeijoilla, since here jA is not a derivational suffix but part of a loanword
• In plural forms of adjectives, -A is mostly lost before the i, e.g. kapea : kape|i|lla. However, -A is changed to -O- in the kkA ending, e.g. rivakka : rivakoissa. In some words, -O- is possible in older language; e.g. Nykysuomen sanakirja describes matala : mataloissa along with the more common matala : matalissa.

Some nouns ending with lA, mA, nA, or rA have two types of plural stems, e.g. pykälä : pykälissä ∼ pykälöissä. Usually the one without O is more common, with some exceptions like omena : omenissa (less often omenoissa). A few adjectives ending with kkä (namely jämäkkä, rämäkkä, and ärhäkkä) have dual inflection, too, with the one with O being more common, e.g. jämäkkä : jämäköillä, less often jämäkillä.

Diphthong variation

The variation uo : oi appears when uo would be followed by an i at the start of a suffix, e.g. indicating plural for nouns or past tense for verbs: suo : soilla (swamp : on swamps), tuon : toin (I bring : I brought).

There is similar variation for the corresponding front vowels: yö : öi, eg. yö → öinen (night → nocturnal), where the variation is caused by the derivative suffix -inen.

The variation ie : ei has similar conditions and origin. Example: tie : teiden (road : of roads).

Other variation in final vowel

The final vowel of a word often changes before a suffix is different ways, in addition to the phenomena described above.

In certain verb forms, 4th person forms, a final vowel a or ä in the verb stem changes to e, e.g. maksa|a : makse|taan : makse|ttu.

Before a derivational suffix, the final vowel of the base word is often lost when the suffix starts with a vowel, e.g. kaiva|a (to dig) → kaiv|o. The final vowel may also change in irregular ways, e.g. reuna → reunu|s. Such phenomena could alternatively be described so that the vowel is part of the suffix (here us) and the suffix causes omission of final vowel: reun|us.

Special changes also sometimes occur at the end of the first part of a compound word, in the compositive forms. E.g., the compound of sika and tauti is sikotauti.

Variation -nen : -se-

Adjectives and nouns that end with nen in nominative singular have se- in inflected forms, for example punainen : punaisen : punaisessa etc. Before the partitive suffix tA and the genitive plural suffix ten, the e is lost, e.g. punaista, punaisten. In the plural stem, the e is lost before i, according to general rules, e.g. punaisissa.

Variation -t- : -s-

In many words, some forms have a t or its consonant gradation counter­part d before the final vowel of the stem, whereas some forms have an s there when an i follows. These words are old and have originally had just t or d, but the t has changed to s before i under certain conditions. Example: vesi : vete|nä : vede|n.

Such words have complicated inflection, since it may involve this variation, consonant gradation, and the variation i : e. The inflection is important because many words of this type, like vesi (water) and käsi (hand; arm) are very common.

A further complication is that words of this type have s in plural forms like vesillä. Such forms are best described so that the -i- is the plural suffix, causing the preceding stem vowel to disappear.

Old nouns ending with -si all have this variation. Newer words lack it, e.g. riisi : riisin (rice).

The variation also appears in verbs, e.g. vastat|a : vasta|s|i.

Vowel stem vs. consonant stem

Many nouns have two different stems across case forms, one ending with a consonant and another ending with that consonant and the vowel e. An example is kannel ∼ kantele, the name of a traditional Finnish harp. Note that the presence of the final e also affects consonant gradation (here nn ∼ nt). This word has in principle two series of forms, kannel : kantelen : kannelta : kantelella etc. versus kantele : kanteleen : kanteletta : kanteleella. The first series has the inflection stem kantele-, the other one has kantelee-. In practice, these series are very often mixed with each other, so that some forms are taken from one series, others from the other.

For example, the word askel (step) has the variant askele, but it is rarely used in the nominative form. Instead, some other forms are used, so we can say e.g. askel askeleelta, mixing the two series (paradigms).

More often, two different stems do not appear as full series but only in some forms. For example, the word nuori has normally the stem nuore- (e.g. in the genitive nuoren), but the partitive has the consonant stem nuor-, in nuorta. Moreover, in the essive, along with the normal form nuorena, the consonant stem form nuorna has also occurred, though it is now used only in poetry, if at all.

Some special forms are based on consonant stems. For example, the normal essive of vuosi (year) with the stems vuote- and vuode- is vuonna, developed via assimilation from the older consonant stem form vuotna. The word form vuonna is very common in the meaning “in the year…”, e.g. vuonna 2014 (in 2014).

For verbs, consonant stems are more common than for nouns and have more variation in the way they differ from the vowel stem. Some inflection forms of verbs have the consonant stem as their basis, others use the vowel stem. This explains much of the stem variation in verbs, e.g. juos|ta (to run) : juokse|n (I run). This is discussed in detail in section The stems of a verb.

Derived words are usually based on the vowel stem of the base word, e.g. nuore|hko (youngish), juokse|nnella (to run around).

The following types of words have a consonant stem:

• Most words with a basic (vowel) stem that ends with a short e, e.g. ääni : ääne|n : ään|tä. This does not include words that end with e in nominative, too (e.g. nalle : nalle|n) or words where the e is preceded by k, p, or v (e.g. kivi : kive|n) or by a consonant combination ending with h, s, or t (e.g. hanhi : hanhe|n), with a few exceptions (e.g. lapsi : lapse|n : las|ta)
• Most verbs with a basic stem (longer than one syllable) that ends with two vowels, e.g. (varat|a :) varaa|n : varat|kaa. This does not include verbs like (luke|a :) lue|n, where the two-vowel combination results from consonant gradation.