Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Proto-Germanic *-ô

→ Old English -a (inherited)
→ Old English -a (inherited)
→ Old High German -o (inherited)
→ Old High German -o (inherited)
→ Gothic -𐍉 (inherited)
→ Gothic -𐌰 (inherited)
→ Old Norse -a (mention)
→ Old Norse -a (mention)
→ Old Norse -i (inherited)
→ Old Dutch -o (inherited)
→ Old Saxon -o (inherited)
→ Old Saxon -o (inherited)