Emily Dickinson Lexicon

AR'BOR, n. [The French express the sense by berceau, a cradle, an arbor, or bower; Sp. emparrado, from parra, a vine raised on stakes, and nailed to a wall. Qu. Chaucer's herber, herbewe, a lodge, coinciding with harbor, which see.]

1. A frame of lattice work, covered with vines, branches of trees, or other plants, for shade; a bower.
2. In botany, a tree, as distinguished from a shrub. The distinction which Linnæus makes, that a tree springs up with a bud on the stem, and a shrub not, is found not to hold universally; and the tree, in popular understanding, differs from the shrub only in size. Arbor forms the seventh family of vegetables in Linnæus's system. [See Tree.]
3. In mechanics, the principal part of a machine, sustaining the rest. Also, the axis or spindle of a machine, as of a crane, or windmill. – Encyc. This in America is called the shaft.