Definify.com

Webster 1913 Edition

Adj.

Of or pertaining to a tree, or to trees; of nature of trees.

Cowley.

Attached to, found in or upon, or frequenting, woods or trees;

as,

arboreal

animals

Woodpeckers are eminently

arboreal

Darwin.

arboreal

pertaining to trees

living in or among trees

arboreal ‎(plural arboreals)

Any tree-dwelling creature.
- 1971, Theo Lang, The difference between a man and a woman
  So, by learning to use their eyes to more and more advantage the arboreals added another treasure to the foundation of human intelligence.