The Collaborative International Dictionary of English v.0.48:

Expensive \Ex*pen"sive\, a.
   1. Occasioning expense; calling for liberal outlay; costly;
      dear; liberal; as, expensive dress; an expensive house or
      family.
      [1913 Webster]

            War is expensive, and peace desirable. --Burke.
      [1913 Webster]

   2. Free in expending; very liberal; especially, in a bad
      sense: extravagant; lavish. [R.]
      [1913 Webster]

            An active, expensive, indefatigable goodness.
                                                  --Sprat.
      [1913 Webster]

            The idle and expensive are dangerous. --Sir W.
                                                  Temple.

   Syn: Costly; dear; high-priced; lavish; extravagant. --
        Ex*pen"sive*ly, adv. -- Ex*pen"sive*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

expensive
    adj 1: high in price or charging high prices; "expensive
           clothes"; "an expensive shop" [ant: cheap,
           inexpensive]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "expensive":
   cheap, costly, dear, dear-bought, extravagant, fancy, high,
   high-priced, immoderate, luxurious, not affordable, of great cost,
   overpriced, precious, premium, priced, priceless, pricey, rich,
   steep, stiff, sumptuous, thrifty, top, uneconomical, unpayable,
   valuable