The Feudal barony of Cardinham (or Honour of Cardinham) was one of the three feudal baronies in Cornwall which existed during the mediaeval era. Its caput was at Cardinham Castle, Cornwall.
The manor of Cardinham (or Care Dynham ) is not mentioned in the Domesday Book (1086) and may thus have acquired its name from its later holders the de Dynham (or Dinham) family which took its name from Dinan in Brittany. The de Cardinham family may thus have been a branch of the de Dynham family of Hartland in Devon to whom the barony later passed from Isolda de Cardinham, for reason unknown. This was the opinion of Leland (died 1552) who writing of Robert de Cardinan as founder of Tywardreath Priory, called him quidam ex Dinamiis ("a certain (man) from the Dinam (family)") Moreover, Lysons (1814) pointed out a further factor giving this opinion validity in that the arms of the two families were similar. Cardinan was later quartered by their descendants the Prideaux family of Prideaux Place, Cornwall, as Sable, three lozenges in fesse ermine, whilst the arms of Dynham were Gules, four lozenges in fesse ermine. It was suggested to Lysons (1814) by Mr Austen, of Place-House, in Fowey, that the Castle was named by its builder, possibly a member of the Dynham family who had inherited the property by marriage to the FitzWilliam heiress, Car - Dinham.