All 4 Uses

arbor
in
The Heritage of the Desert
(Edited)

His rider bent low to dodge the vines of the arbor, and reined in before the porch to slip out of the saddle with the agility of an Indian.
Chpt 2 *

arbor = a framework that supports climbing plants; or a shady rest area made by such a framework or by trees and shrubs
Hide Bolly and Silvermane in the little arbor down in the orchard.
Chpt 19
Later I'll hide Bolly and Silvermane in the arbor.
Chpt 19
He paced his hidden walk behind the arbor, at every turn glancing sharply up and down the road.
Chpt 19

Definitions:

(1) (arbor as in: shaded arbor)
a framework that supports climbing plants; or a shady rest area made by such a framework or by trees and shrubs

The framework of an arbor is generally thought of as a wood lattice made to support vines, but it can also be a natural framework such as trees.
(2) (meaning too rare to warrant focus)
Less commonly arbor can be used as a proper noun to reference a location such as Ann Arbor, Michigan. As a common noun, it can also reference various types of rotating machine shafts.