From Proto-Slavic *kostrьcь which is from Proto-Slavic *kostra (“skeleton”). This probably comes from several intermingling sources: from Proto-Slavic *kostr-, *kostь (“bone”) and at the same time the root *kes-, which is from Proto-Indo-European *kes- (“to scratch”). The present Czech form kostrč was probably also influenced by the word trčet (“stick out”). Compare kost, kostra and kostrbatý.
- kostřec (obsolete)