The Collaborative International Dictionary of English v.0.48:

Increase \In*crease"\, v. i. [imp. & p. p. Increased; p. pr. &
   vb. n. Increasing.] [OE. incresen, encresen, enrescen, OF.
   encreistre, fr. L. increscere; pref. in- in + crescere to
   grow. See Crescent, and cf. Decrease.]
   [1913 Webster]
   1. To become greater or more in size, quantity, number,
      degree, value, intensity, power, authority, reputation,
      wealth; to grow; to augment; to advance; -- opposed to
      decrease.
      [1913 Webster]

            The waters increased and bare up the ark. --Gen.
                                                  vii. 17.
      [1913 Webster]

            He must increase, but I must decrease. --John iii.
                                                  30.
      [1913 Webster]

            The heavens forbid
            But that our loves and comforts should increase,
            Even as our days do grow!             --Shak.
      [1913 Webster]

   2. To multiply by the production of young; to be fertile,
      fruitful, or prolific.
      [1913 Webster]

            Fishes are more numerous or increasing than beasts
            or birds, as appears by their numerous spawn. --Sir
                                                  M. Hale.
      [1913 Webster]

   3. (Astron.) To become more nearly full; to show more of the
      surface; to wax; as, the moon increases.
      [1913 Webster]

   Increasing function (Math.), a function whose value
      increases when that of the variable increases, and
      decreases when the latter is diminished; also called a
      monotonically increasing function.

   Syn: To enlarge; extend; multiply; expand; develop; heighten;
        amplify; raise; enhance; spread; aggravate; magnify;
        augment; advance.

   Usage: To Increase, Enlarge, Extend. Enlarge implies to
          make larger or broader in size. Extend marks the
          progress of enlargement so as to have wider
          boundaries. Increase denotes enlargement by growth and
          internal vitality, as in the case of plants. A kingdom
          is enlarged by the addition of new territories; the
          mind is enlarged by knowledge. A kingdom is extended
          when its boundaries are carried to a greater distance
          from the center. A man's riches, honors, knowledge,
          etc., are increased by accessions which are made from
          time to time.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

increased \increased\ adj.
   1. made greater in size or amount or degree. Opposite of
      decreased. [Narrower terms: augmented ; {exaggerated,
      hyperbolic, inflated; exaggerated, magnified, enlarged
      ; {raised(prenominal), inflated ]
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

increased
    adj 1: made greater in size or amount or degree [ant:
           {decreased, reduced]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "increased":
   accelerated, aggrandized, aggravated, ampliate, amplified, annoyed,
   augmented, beefed-up, bloated, boosted, broadened, built-up,
   crescendoed, deepened, deliberately provoked, elevated, embittered,
   enhanced, enlarged, exacerbated, exasperated, expanded, extended,
   heated up, heightened, hiked, hotted up, inflated, intensified,
   irritated, jazzed up, magnified, manifold, multifold, multiple,
   multiplied, polynomial, proliferated, provoked, raised, reinforced,
   soured, spread, stiffened, strengthened, swollen, tightened, upped,
   widened, worse, worsened