[syn: arbor, arbour, bower, pergola]
The Collaborative International Dictionary of English v.0.48:
Arbor \Ar"bor\, n. [OE. herber, herbere, properly a garden of
   herbs, F. herbier, fr. L. herbarium. See Herb, and cf.
   Herbarium.]
   A kind of latticework formed of, or covered with, vines,
   branches of trees, or other plants, for shade; a bower. --Sir
   P. Sidney.
   [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Arbor \Ar"bor\, n. [Written also arbour.] [L., a tree, a beam.]
   1. (Bot.) A tree, as distinguished from a shrub.
      [1913 Webster]
   2. [Cf. F. arbre.] (Mech.)
      (a) An axle or spindle of a wheel or opinion.
      (b) A mandrel in lathe turning. --Knight.
          [1913 Webster]
WordNet (r) 3.0 (2006):
arbor
    n 1: tree (as opposed to shrub)
    2: any of various rotating shafts that serve as axes for larger
       rotating parts [syn: spindle, mandrel, mandril,
       arbor]
    3: a framework that supports climbing plants; "the arbor
       provided a shady resting place in the park" [syn: arbor,
       arbour, bower, pergola]
Moby Thesaurus II by Grady Ward, 1.0:
38 Moby Thesaurus words for "arbor":
   alcove, axis, axle, axle bar, axle shaft, axle spindle, axle-tree,
   belvedere, bower, casino, conservatory, distaff, fulcrum, gazebo,
   gimbal, glasshouse, greenhouse, gudgeon, hinge, hingle, hub, kiosk,
   lathhouse, mandrel, nave, oarlock, pergola, pin, pintle, pivot,
   pole, radiant, retreat, rowlock, spindle, summerhouse, swivel,
   trunnion