A rounded or conical heap of stones erected by early inhabitants of the British Isles, apparently as a sepulchral monument.
A pile of stones heaped up as a landmark, to guide travelers on land or at sea, or to arrest attention, as in surveying, or in leaving traces of an exploring party, etc.
A cairn terrier.
Come on.
An exclamation of support or approval, usually for a sporting (football) team.
1956 September 10, "Carn the Magpies!", The Argus