IPA: /ˈkɜːrbstoʊn/
KK: /ˈkɜrbˌstoʊn/
Not trained or experienced; lacking sophistication or professionalism.
The curbstone commentator shared his opinions without any formal training.
A stone or a row of stones that forms the edge of a street or sidewalk, helping to keep the road and pavement separate.
The children played near the curbstone, careful not to run into the street.
Curbstone is formed from "curb" (from Old French *curbe*, meaning to bend or curve) and "stone" (from Old English *stan*, meaning rock or stone). The word refers to a stone that forms the edge of a sidewalk, typically curving at the street.
Think of a 'curb' that 'bends' at the edge of a street, and 'stone' that refers to the material — together, they describe a stone that curves at the sidewalk's edge.