Latin serius

← Old English swǣr (cognate)

← German schwer (cognate)

← English sweer (link)

← Proto-Indo-European (inherited)

← Proto-Indo-European *swer- (derived)

← Proto-Italic *swerjos (inherited)

← Lithuanian sverti (cognate)

← Lithuanian svarùs (mention)

→ Norwegian Bokmål seriøs (derived)

→ Norwegian Nynorsk seriøs (derived)