Forest

A forest was an area with a large number of trees. Rivers were the only body of water in forests. (TV: The Doctor's Wife) Vashta Nerada usually lived in forests. (TV: Forest of the Dead) Forests located in hot climates were generally known as jungles.

The trees of Cheem were introduced as "the forest of Cheem." (TV: The End of the World)

Forests on Earth
Amongst forests on Earth were:
 * Blackdown Woods (TV: Human Nature)
 * Forest of Fear (TV: An Unearthly Child)
 * Oxley Woods (TV: Spearhead from Space)
 * Roundstone Wood (TV: Small Worlds)
 * Sherwood Forest (TV: The Last Oak Tree)
 * Swallow Woods (PROSE: The Way Through the Woods)

Forests on other planets

 * The Gamma Forests were located on an unnamed planet. (TV: A Good Man Goes to War)
 * There were also forests on Earth's moon. (PROSE: Imperial Moon)
 * In 5345, the Eleventh Doctor, along with Cyril, Lily and Madge Arwell, visited a forest on an unnamed planet. (TV: The Doctor, the Widow and the Wardrobe)
 * The section of a pocket universe in which the Eleventh Doctor once got stuck was entirely forest. (TV: Hide)