Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Cornish seythen

→ Breton sizhun (cognate)
→ Cornish pennseythen (prefix)
→ Cornish pednseythen (prefix)
→ Cornish seythennow (suffix)
→ Cornish seythednow (suffix)