Cairn and Megalith

Cairn noun - A mound of stones piled up as a memorial or to mark a boundary or path.

Megalith and cairn are semantically related. In some cases you can use "Megalith" instead a noun "Cairn".

Megalith noun - Memorial consisting of a very large stone forming part of a prehistoric structure (especially in western Europe).

Cairn and megalith are semantically related. Sometimes you can use "Cairn" instead a noun "Megalith".