Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Old Irish secht
← Proto-Celtic *sextam (inherited)
← Proto-Indo-European *septḿ̥ (inherited)

→ Old English seofon (cognate)
→ Irish seacht (inherited)
→ Irish seachtó (mention)
→ Scottish Gaelic seachd (inherited)
→ Manx shiaght (inherited)
→ Middle Irish secht (inherited)