timber

Timber is wood cut and prepared for building — planks stacked in a yard, beams going up on a house frame, the smell of sawn pine. It is the tree after the saw has finished with it.

Britain says timber where America says lumber, so a British builder orders timber and an American one drives to the lumber yard. In the plural, timbers are the heavy structural beams of a roof or a ship: the ship's timbers groaned all night. Timber! is what you shout as a tree comes down, so that everyone below gets clear. It works as an adjective as well — a timber frame, a timber floor, timber cladding. In the main sense it is uncountable: you buy some timber, not two timbers, unless you mean the beams themselves.