The Collaborative International Dictionary of English v.0.48:

Expand \Ex*pand"\, v. i.
   To become widely opened, spread apart, dilated, distended, or
   enlarged; as, flowers expand in the spring; metals expand by
   heat; the heart expands with joy. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Expand \Ex*pand"\, v. t. [imp. & p. p. Expanded; p. pr. & vb.
   n. Expanding.] [L. expandere, expansum; ex out + pandere to
   spread out, to throw open; perh. akin to E. patent. Cf.
   Spawn.]
   1. To lay open by extending; to open wide; to spread out; to
      diffuse; as, a flower expands its leaves.
      [1913 Webster]

            Then with expanded wings he steers his flight.
                                                  --Milton.
      [1913 Webster]

   2. To cause the particles or parts of to spread themselves or
      stand apart, thus increasing bulk without addition of
      substance; to make to occupy more space; to dilate; to
      distend; to extend every way; to enlarge; -- opposed to
      contract; as, to expand the chest; heat expands all
      bodies; to expand the sphere of benevolence.
      [1913 Webster]

   3. (Math.) To state in enlarged form; to develop; as, to
      expand an equation. See Expansion, 5.
      [1913 Webster]

WordNet (r) 3.0 (2006):

expand
    v 1: extend in one or more directions; "The dough expands" [syn:
         expand, spread out] [ant: contract, shrink]
    2: become larger in size or volume or quantity; "his business
       expanded rapidly"
    3: make bigger or wider in size, volume, or quantity; "expand
       the house by adding another wing"
    4: grow vigorously; "The deer population in this town is
       thriving"; "business is booming" [syn: boom, thrive,
       flourish, expand]
    5: exaggerate or make bigger; "The charges were inflated" [syn:
       inflate, blow up, expand, amplify]
    6: add details, as to an account or idea; clarify the meaning of
       and discourse in a learned way, usually in writing; "She
       elaborated on the main ideas in her dissertation" [syn:
       elaborate, lucubrate, expatiate, exposit, enlarge,
       flesh out, expand, expound, dilate] [ant:
       abbreviate, abridge, contract, cut, foreshorten,
       reduce, shorten]
    7: expand the influence of; "The King extended his rule to the
       Eastern part of the continent" [syn: extend, expand]