Lithuanian tvirtas

← Proto-Balto-Slavic *twirˀ- (inherited)

← Proto-Indo-European *twerH- (inherited)

← Proto-Indo-European *tworH-o- (cognate)

← Proto-Indo-European *twerH- (cognate)

← Proto-Indo-European *twōrH- (cognate)

← Proto-Indo-European *turH-eh₁yé- (cognate)

← Lithuanian ãptvaras (link)

← Lithuanian tvérti (link)

← Lithuanian tvorà (link)

← Lithuanian turėti (link)

← Latvian tvirts (cognate)

← Polish twardy (cognate)

← Proto-Slavic *tvьrdъ (link)