-uus/-yys

Abstract Nouns (-uus/-yys)

Level 4

The suffix -uus / -yys creates abstract nouns from adjectives (e.g., vanha 'old' → vanhuus 'old age'). It follows vowel harmony and uses the stem -uude- / -yyde- for most cases.

How It Works

The -uus / -yys suffix is highly productive, meaning it can be used to create new words for modern concepts.

1. Formation Rules:

  • Adjectives ending in -a/-ä: The final vowel is replaced: syvä (deep) → syvyys (depth).
  • Adjectives ending in -i: The final vowel is replaced: suuri (great) → suuruus (greatness). Exception: uusi (new) → uutuus (novelty). Use the stem uut- plus -uus: uutuus. Do not concatenate uute- + -us.
  • Adjectives ending in -is: Some change the ending to -e- (kaunis → kauneus), but many retain the -i- (valmis → valmius).
  • Adjectives ending in -ea/-eä: The final vowel is dropped: korkea (high) → korkeus (height).
  • Adjectives ending in -inen: The ending becomes -isuus / -isyys: onnellinen (happy) → onnellisuus (happiness).
  • The Related -us/-ys Pattern: Some bases use the short-vowel suffix. With vapaa, first shorten the final long vowel: vapa- + -us → vapaus. Other useful patterns are terve + -ys → terveys and helppo + -us → helppous. Learn the base stem and suffix together rather than adding an ending to every dictionary form unchanged.

2. Inflection and Gradation:
These nouns belong to a specific stem type. In the nominative, they end in -s. When adding case endings like the genitive, the weak stem becomes -uude- / -yyde- for unshortened words, and -ude- / -yde- for shortened words (e.g., vapauden). The strong stem is -uute- / -yyte- (unshortened) or -ute- / -yte- (shortened), which is used in cases like the illative (e.g., suuruuteen, vapauteen). In the partitive singular, the ending -ta / -tä attaches to the consonant stem -uut- / -yyt- for double-vowel words (e.g., suuruutta), and -ut- / -yt- for shortened words (e.g., vapautta).

3. Plural Stem:
For plural cases (other than the nominative plural), the stem changes to -uuksi- / -yyksi- for unshortened words (e.g., suuruuksia), and -uksi- / -yksi- for shortened words (e.g., vapauksissa).

4. Usage Nuance:
While many of these nouns are abstract and often uncountable, they are frequently used in the plural when referring to specific instances (e.g., mahdollisuudet 'possibilities', vaikeudet 'difficulties'). They are used in all registers, from everyday talk (terveys 'health') to academic writing (todellisuus 'reality').

Noun Bases and Stem Changes
The same family also derives nouns from nouns: ystävä → ystävyys (friendship), lapsi → lapsuus (childhood), and äiti → äitiys (motherhood). Use the strong stem where the base has gradation, as in helppo → helppous, rikas → rikkaus, and kallis → kalleus. Base-specific changes still matter: compare avoin → avoimuus and rahaton → rahattomuus.

Examples (5)

  1. Terveys on tärkeämpää kuin raha.

    Health is more important than money.

    Word by Word: Health is more-important than money.

    'Terveys' (health) is derived from the adjective 'terve' (healthy).

  2. Hän arvostaa sananvapautta.

    He values freedom of speech.

    Word by Word: He values word-freedom.

    'Vapautta' is the partitive form of 'vapaus' (freedom). Note that the partitive ending '-ta' attaches to the consonant stem 'vapaut-'.

  3. Lapset nauttivat lapsuuden leikeistä.

    Children enjoy the games of childhood.

    Word by Word: Children enjoy childhood's games.

    'Lapsuuden' is the genitive form of 'lapsuus' (childhood). The 't' in the stem changes to 'd'.

  4. Vuoren korkeus on kaksi kilometriä.

    The height of the mountain is two kilometers.

    Word by Word: Mountain's height is two kilometers.

    'Korkeus' (height) comes from the adjective 'korkea' (high/tall).

  5. Pimeys pelottaa pientä lasta.

    The darkness scares the small child.

    Word by Word: Darkness scares small child.

    'Pimeys' (darkness) comes from 'pimeä' (dark).

Common Mistakes

  • Confusing the genitive stems of deadjectival and deverbal nouns ending in -us/-ys.

    vapauksen
    vapauden

    Learners often confuse deadjectival nouns (derived from adjectives, like 'vapaus' from 'vapaa') with deverbal nouns (derived from verbs, like 'vastaus' from 'vastata'). Deadjectival nouns use the '-uude-/-yyde-' stem (vapaus -> vapauden), while deverbal nouns use the '-ukse-/-ykse-' stem (vastaus -> vastauksen).

  • Violating vowel harmony.

    syvyus
    syvyys

    Because 'syvä' (deep) contains front vowels, the suffix must also use front vowels (-yys).

  • Assuming all -is adjectives change 'i' to 'e'.

    valmeus
    valmius

    While some adjectives ending in -is change 'i' to 'e' (kaunis -> kauneus), many retain the 'i' (valmis -> valmius, tiivis -> tiiviys).

How It Connects

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-uus/-yysLevel 4Abstract Nouns (-uus/-yys)

Learn This First

To understand the formation of abstract nouns with -uus/-yys, you need to be comfortable with Finnish vowel harmony to choose the correct suffix variant. Additionally, you must understand how adjective stems change when suffixes are added, as many adjectives undergo stem modifications before the -uus/-yys ending is attached.

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-uus-yys