The Collaborative International Dictionary of English v.0.48:

Mathematical \Math`e*mat"ic*al\, a. [See Mathematic.]
   Of or pertaining to mathematics; according to mathematics;
   hence, theoretically precise; accurate; as, mathematical
   geography; mathematical instruments; mathematical exactness.
   -- Math`e*mat"ic*al*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mathematical
    adj 1: of or pertaining to or of the nature of mathematics; "a
           mathematical textbook"; "slide rules and other
           mathematical instruments"; "a mathematical solution to a
           problem"; "mathematical proof"
    2: relating to or having ability to think in or work with
       numbers; "tests for rating numerical aptitude"; "a
       mathematical whiz" [syn: numerical, mathematical] [ant:
       verbal]
    3: beyond question; "a mathematical certainty"
    4: statistically possible though highly improbable; "have a
       mathematical chance of making the playoffs"
    5: characterized by the exactness or precision of mathematics;
       "mathematical precision"

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "mathematical":
   algebraic, analytic, arithmetical, close, constant, delicate,
   direct, even, exact, express, faithful, fine, geometric, inerrable,
   inerrant, infallible, micrometrically precise, microscopic, nice,
   numeric, pinpoint, precise, refined, religious, religiously exact,
   rigid, rigorous, scientific, scientifically exact, severe, square,
   strict, subtle, undeviating, unerring