Umlaut in the plural number

DA7

 

Certain nouns form the plural number with the addition of umlaut to their stem vowel. This is the case with types A, B and C of plural number formation.

 

Types of plural Singular Plural with umlaut
       
Type A ending -e    
  Stadt Städte
Bach Bäche
Knopf Knöpfe
Ball Bälle
       
Type B ending -er    
  Haus Häuser
Irrtum Irrtümer
Bad Bäder
Mann Männer
       
Type C without ending    
  Vater Väter
Boden Böden
Vogel Vögel
Mutter Mütter