(idiomatic) A film or novel depicting adventures of characters in the American Old West; a western.

(dated, UK, university slang) To close one's door as an indication that visitors are not welcome.

A tree, Quercus petraea, the sessile oak. / Wood of the tree.

Initialism of of a kind.

(usually countable) An oak tree with wood of a red tint, with leaves that have pointed lobes, Quercus rubra, native to eastern North America.

The tree Quercus bicolor.

The tree Quercus palustris. / The tree Quercus ellipsoidalis.

The tree Quercus coccinea.

the red oak, Quercus rubra.

Alternative form of bur oak