Built with a frame of heavy wooden beams — or, more often in the way people actually use the word, having those beams visible on the outside of the building. The picture almost everyone has is the old English or German country house with dark beams crossing white walls: that is a 'half-timbered' house, and honestly 'half-timbered' is the phrase you will meet far more than plain 'timbered'. The 'half' means the beam frame is filled in between with something else — plaster, brick, mud and straw — so you see wood and wall in stripes. There is a second, quieter use that surprises people: land can be timbered, meaning it is covered with trees suitable for cutting into wood. 'A well-timbered valley' is a forestry phrase, not an architecture one. And in older writing 'heavily timbered' describes thick forest. Note that 'timber' itself is the British word for what Americans usually call 'lumber' — wood prepared for building.