'hearthstone' originates from Old English, specifically the words 'heorð' meaning 'hearth' and 'stān' meaning 'stone'.

'heorðstān' transformed into the Middle English word 'hearthstane', and eventually became the modern English word 'hearthstone'.

Initially, it meant 'a stone forming part of a hearth', and this meaning has largely remained the same in modern usage.