k / c

K and C Alternation

Level 3

The k:c alternation is a mandatory sound change in Polish. It occurs when a word ending in k meets specific grammatical endings, shifting the 'k' sound to a 'c' (pronounced like 'ts').

How It Works

The k:c alternation (oboczność k:c) is a fundamental part of Polish morphology. It is not optional; using a 'k' where a 'c' is required is a noticeable grammatical error.

1. Feminine Nouns (Dative & Locative Singular)
When a feminine noun ends in -ka, the stem changes to -ce in the Dative and Locative cases.

  • ręka (hand) → ręce
  • matka (mother) → matce
  • biblioteka (library) → bibliotece

2. Masculine Personal Nouns (Nominative Plural)
When referring to groups of men (or mixed groups), nouns ending in -k change to -cy in the Nominative plural.

  • Polak (Pole) → Polacy
  • robotnik (worker) → robotnicy

3. Masculine Personal Adjectives (Nominative Plural)
Adjectives describing masculine personal nouns also undergo this shift before the plural ending.

  • polski (Polish) → polscy
  • wysoki (tall) → wysocy

Important Note: This alternation does not happen in the Locative for masculine or neuter nouns (e.g., w parku, not w parce). It is also distinct from the k:cz shift used in diminutives (e.g., ręka → rączka).

Examples (5)

  1. Książka leży na półce.

    The book is lying on the shelf.

    Word by Word: Book lies on shelf.

    The noun 'półka' (shelf) changes its 'k' to 'c' because it is in the Locative case after the preposition 'na'.

  2. Moi polscy koledzy mieszkają w Warszawie.

    My Polish colleagues live in Warsaw.

    Word by Word: My Polish colleagues live in Warsaw.

    The adjective 'polski' changes to 'polscy' to agree with the masculine personal plural noun 'koledzy'.

  3. Polacy bardzo lubią pierogi.

    Poles like pierogi very much.

    Word by Word: Poles very like pierogi.

    The noun 'Polak' (a Pole) becomes 'Polacy' in the plural because it refers to people (masculine personal).

  4. Daję ten prezent mojej matce.

    I am giving this gift to my mother.

    Word by Word: I give this gift my mother.

    The noun 'matka' changes to 'matce' in the Dative case (the recipient).

  5. Wszyscy robotnicy skończyli pracę.

    All the workers finished work.

    Word by Word: All workers finished work.

    The noun 'robotnik' (worker) changes to 'robotnicy' in the Nominative plural.

Common Mistakes

  • Using the 'k' stem in the feminine Locative case.

    Książka jest w biblioteke.
    Książka jest w bibliotece.

    Feminine nouns ending in -ka MUST change to -ce in the Locative case. 'Biblioteke' is incorrect.

  • Forgetting the mutation in the masculine personal plural.

    Moi polski koledzy.
    Moi polscy koledzy.

    When describing a group of men, the adjective must undergo the k:c shift. 'Polski' is singular or non-personal plural.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

k / cLevel 3K and C Alternation

Learn This First

Learn Consonant Softening Before I before K And C Alternation.