Old English sūr

→ English sour (inherited)

→ Old English sure (mention)

→ Old English unsur (prefix)

→ Old English surnes (affix)

→ Old English surian (suffix)

→ Middle English sour (inherited)

→ Middle English sowre (inherited)

→ Middle English soure (inherited)

→ Old High German sur (mention)

→ Old Norse súrr (cognate)