Old English þearf

← Proto-Germanic *þarbō (inherited)

→ English thair (inherited)

→ Old English fyrenþearf (affix)

→ Old English sawelþearf (compound)

→ Middle English tharf (inherited)

→ Faroese tarvur (cognate)

→ Faroese tørvur (cognate)

→ Norwegian Bokmål tarv (cognate)

→ Norwegian Nynorsk torv (cognate)

→ Swedish tarv (cognate)