"tree-garden," 1838, from Latin arboretum, literally "a place grown with trees," from arbor "tree," which is of unknown origin, + -etum, suffix used to form the names of [..]

A garden with a large collection of trees and shrubs cultivated for scientific or educational purposes. arborist:

A group of trees

Botanical gardens devoted to the cultivation and exhibition of trees and other woody plants, rare or otherwise.

A place where an extensive variety of trees are cultivated for scientific educa­tional, or ornamental purposes

Organized collection of trees and other woody plants; a garden with a large collection of trees and shrubs cultivated for scientific or educational purposes. Arboriculture

An Arboretum is a botanical garden that mainly features woody plants: trees, bushes, and vines. The U.S. National Arboretum now has its own herbarium. 

An area devoted to specimen plantings of trees and shrubs.

n. A botanical garden or place devoted to the cultivation of trees or shrubs.

(n) a facility where trees and shrubs are cultivated for exhibition

A collection of specimen trees.

A place where many kinds of trees and shrubs are grown for scientific and educational purposes. Arboretum

<botany> A place in which a collection of rare trees and shrubs is cultivated for scientific or educational purposes. Origin: L, a place grown with trees. (01 Mar 1998)

An area devoted to specimen plantings of trees and shrubs.