Several meaning/origins.

1. A corncob: corn on the cob.

2. A male swan.

3. A thickset, stocky, short-legged horse.

4. A small lump or mass, as of coal.

5. A mixture of clay and straw used as a building material

The origin of the building material (adobe) cob is probably from:

COB: a rounded heap or mass; a small heap of anything

"Cob" is a mixture of clay and straw used as a building material.

To make a cob house you first make a wooden frame for the house and erect it on the foundations. The walls are then filled with wattle (a construction of poles intertwined with twigs, reeds, or branches) and these are then daubed by hand with the cob to make a solid wall.

Cob

corn on the cob! hence why maize is sometimes called corn.

cob