All 3 Uses of

arbor

in

The Yellow Wallpaper

I never saw such a garden—large and shady, full of box-bordered paths, and lined with long grape-covered arbors with seats under them.
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arbors = a framework that supports climbing plants

Out of one window I can see the garden, those mysterious deepshaded arbors, the riotous old-fashioned flowers, and bushes and gnarly trees.

arbors = frameworks that support climbing plants

I always fancy I see people walking in these numerous paths and arbors, but John has cautioned me not to give way to fancy in the least.

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)
Much more rarely, an arbor can be used as a proper noun to reference a location. As a common noun, it can also reference various types of rotating machine shafts.