Noun

1. The wood from any dicotyledonous tree, without regard to its hardness.

   Balsa is a hardwood, but a soft hardwood.

2. (in more general use) As the preceding but limited to those that are commercial timbers, and are at least average in hardness.

   Ash, hickory and oak are some of the most prominent domestic hardwoods.

3. The tree or tree species that yields the preceding.

   This hardwood has been planted extensively throughout the hills here.

4. A joint term for the commercial timbers, without distinguishing which.

   You should have used hardwood for this window sill instead of this junk.