Is a pile of wood and air

That measures one hundred twenty-eight cubic feet.

Stacked loose enough so that a squirrel can get through it,

but tight enough to stop the cat that's chasing it.

The most common configuration for this stack, is a pile of wood and air, four feet wide, four feet high and eight feet long.

A cord is also eighty cubic feet of SOLID wood. Cut to any length, width and height that equals eighty cubic feet.

The latter is much harder to get to the fire place.