Proto-Celtic *kū

→ Breton ki (inherited)

→ Welsh ci (inherited)

→ Welsh cŵn (inherited)

→ Irish cú (inherited)

→ Scottish Gaelic coin (derived)

→ Scottish Gaelic cù (inherited)

→ Galician cuza (derived)

→ Galician cuzo (derived)

→ Manx coo (inherited)

→ Cornish ki (inherited)

→ Middle Irish cú (inherited)

→ Primitive Irish ᚉᚒᚅᚐ (inherited)

→ Old Irish cú (inherited)

→ Old Irish cuilén (mention)

→ Old Irish Conall (compound)