Timber is a term used to describe clusters of trees. It is also used to describe wood throughout its processing from the time it is cut down to the time it is used as a structural material.
The word TIMBER! is also used as an exclamation when a tree falls. It is used to warn others working in the same area that a tree is going to fall down and that they should take care to get out of the way of its path. People may also use the term in this way to refer to other objects that fall.