The Collaborative International Dictionary of English v.0.48:

Foliage \Fo"li*age\, n. [OF. foillage, fueillage, F. feuillage,
   fr. OF. foille, fueille, fueil, F. feulle, leaf, L. folium.
   See 3d Foil, and cf. Foliation, Filemot.]
   [1913 Webster]
   1. Leaves, collectively, as produced or arranged by nature;
      leafage; as, a tree or forest of beautiful foliage.
      [1913 Webster]

   2. A cluster of leaves, flowers, and branches; especially,
      the representation of leaves, flowers, and branches, in
      architecture, intended to ornament and enrich capitals,
      friezes, pediments, etc.
      [1913 Webster]

   Foliage plant (Bot.), any plant cultivated for the beauty
      of its leaves, as many kinds of Begonia and Coleus.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Foliage \Fo"li*age\, v. t.
   To adorn with foliage or the imitation of foliage; to form
   into the representation of leaves. [R.] --Drummond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

foliage
    n 1: the main organ of photosynthesis and transpiration in
         higher plants [syn: leaf, leafage, foliage]
    2: (architecture) leaf-like architectural ornament [syn:
       foliation, foliage]