4. stems ending in -c (paradigm vac-, f., speech)
 
  Sg. Du. Pl.
Nom. vak vacau vacah
Acc. vacam vacau vacah
Ins. vaca vagbhyam vagbhih
Dat. vace vagbhyam vagbhyah
Abl. vacah vagbhyam vagbhyah
Gen. vacah vacoh vacam
Loc. vaci vacoh vaksu
Voc. vak vacau vacah