Proto-Slavic *krěpostь

→ Belarusian крэпасць (inherited)

→ Bulgarian крепост (inherited)

→ Old Church Slavonic крѣпость (inherited)

→ Macedonian крепост (inherited)

→ Russian крепость (inherited)

→ Serbo-Croatian krepost (inherited)

→ Serbo-Croatian krepkost (inherited)