Proto-Germanic *þewernǭ

→ English tern (derived)

→ Cimbrian diarn (inherited)

→ Cimbrian diirna (inherited)

→ German Dirne (inherited)

→ German Deern (derived)

→ Faroese terna (derived)

→ Icelandic þerna (inherited)

→ Mòcheno diarn (inherited)

→ Dutch deerne (inherited)

→ Old Norse þerna (derived)

→ Swedish tärna (derived)