Similar to my entry on beinn, càrn is a Gaelic word that might see in different areas and monuments throughout Scotland.
A càrn is a “a heap of stones”, according to Am Faclair Beag. It is from this word that the word Cairn comes from. A Cairn is a pile of stones that often serves as a monument for one purpose or another.
Cairns exist in Scotland in several places for various reasons. In ancient times, they might have been used to note significant landmarks; for navigational purposes; to note astrological phenomena; or signify a burial place, which is likely the more well-know reason.
Before battles, Highland Clan members might place another stone upon a Cairn. If they returned battle, they would take their stone back, so that the stones left at the Cairn would build a memorial for the deceased.
A famous burial ground Cairn is the Clava Cairns in the Highlands of Scotland, which I’ve done an entry on here.