Old Norse tjǫrn

← Proto-Germanic *ternō (inherited)

← Proto-Germanic *turnaz (mention)

← Proto-Indo-European *der- (root)

→ English tarn (derived)

→ Faroese tjørn (inherited)

→ Icelandic tjörn (inherited)

→ Norwegian Bokmål tjern (mention)

→ Norwegian Bokmål tjørn (inherited)

→ Norwegian Bokmål kjønn (mention)

→ Norwegian Nynorsk tjern (mention)

→ Norwegian Nynorsk tjørn (mention)

→ Swedish tjärn (derived)