Polski — Vowel alternations in inflection

In Polish, certain vowels change regularly when a word is declined or conjugated. The most frequent are ó:o (stół → stołu), ą:ę (ząb → zęba, ręka → rąk) and the "fleeting e" e:∅ (pies → psa).

How it works

✓ Rule

When an ending is added or dropped, ó shifts to o (stół → stołu), ą shifts to ę (ząb → zęba), and a "fleeting e" present in the base form disappears (pies → psa). The alternation follows the stem, not the meaning.

Examples

Common vowel alternations
Alternation	Example	Meaning
ó : o	stół → stołu	table (gen. sg.)
ó : o	róg → rogu	horn / corner (gen. sg.)
ą : ę	ząb → zęba	tooth (gen. sg.)
ę : ą	ręka → rąk	hand (gen. pl.)
e : ∅	pies → psa	dog (gen. sg.)
e : ∅	sen → snu	sleep / dream (gen. sg.)

Good to know

⚠ Note

The shift can also go the other way: in ręka → rąk the ę becomes ą in the genitive plural. And never keep the fleeting e in inflected forms — it is psa, not "piesa".