The Collaborative International Dictionary of English v.0.48:

Advance \Ad*vance"\, n. [Cf. F. avance, fr. avancer. See
   Advance, v.]
   1. The act of advancing or moving forward or upward;
      progress.
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   2. Improvement or progression, physically, mentally, morally,
      or socially; as, an advance in health, knowledge, or
      religion; an advance in rank or office.
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   3. An addition to the price; rise in price or value; as, an
      advance on the prime cost of goods.
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   4. The first step towards the attainment of a result;
      approach made to gain favor, to form an acquaintance, to
      adjust a difference, etc.; an overture; a tender; an
      offer; -- usually in the plural.
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            [He] made the like advances to the dissenters.
                                                  --Swift.
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   5. A furnishing of something before an equivalent is received
      (as money or goods), towards a capital or stock, or on
      loan; payment beforehand; the money or goods thus
      furnished; money or value supplied beforehand.
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            I shall, with pleasure, make the necessary advances.
                                                  --Jay.
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            The account was made up with intent to show what
            advances had been made.               --Kent.
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   In advance
      (a) In front; before.
      (b) Beforehand; before an equivalent is received.
      (c) In the state of having advanced money on account; as,
          A is in advance to B a thousand dollars or pounds.
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WordNet (r) 3.0 (2006):

in advance
    adv 1: ahead of time; in anticipation; "when you pay ahead (or
           in advance) you receive a discount"; "We like to plan
           ahead"; "should have made reservations beforehand" [syn:
           ahead, in advance, beforehand]
    adj 1: situated ahead or going before; "an advance party"; "at
           that time the most advanced outpost was still east of the
           Rockies" [syn: advance(a), advanced(a), in
           advance(p)]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "in advance":
   ahead, ahead of time, ante, before, beforehand, beforetime,
   betimes, early, first, fore, foremost, foresightedly, forward,
   headmost, in advance of, in anticipation, in anticipation of,
   in front, in preparation for, in the forefront, in the foreground,
   in the front, in the lead, on loan, on security, precociously,
   previous, previous to, prior to, to the fore, to the front,
   up ahead