The Collaborative International Dictionary of English v.0.48:

Calculation \Cal`cu*la"tion\ (-l[=a]"sh[u^]n), n. [OE.
   calculation, fr. L. calculatio; cf. OF. calcucation.]
   1. The act or process, or the result, of calculating;
      computation; reckoning, estimate. "The calculation of
      eclipses." --Nichol.
      [1913 Webster]

            The mountain is not so his calculation makes it.
                                                  --Boyle.
      [1913 Webster]

   2. An expectation based on circumstances.
      [1913 Webster]

            The lazy gossips of the port,
            Abhorrent of a calculation crost,
            Began to chafe as at a personal wrong. --Tennyson.
      [1913 Webster]

WordNet (r) 3.0 (2006):

calculation
    n 1: the procedure of calculating; determining something by
         mathematical or logical methods [syn: calculation,
         computation, computing]
    2: problem solving that involves numbers or quantities [syn:
       calculation, computation, figuring, reckoning]
    3: planning something carefully and intentionally; "it was the
       deliberation of his act that was insulting" [syn:
       calculation, deliberation]

Moby Thesaurus II by Grady Ward, 1.0:

148 Moby Thesaurus words for "calculation":
   adding, aforethought, amount, answer, appraisal, appraisement,
   approach, approximation, arithmetic, arrangement, assessment,
   assize, assizement, attack, blueprint, blueprinting,
   calculatedness, calculus, canniness, care, careful consideration,
   carefulness, casting, caution, cautiousness, charting, ciphering,
   circumspection, computation, conception, contrivance, correction,
   count, counting, deliberate stages, deliberateness, deliberation,
   design, determination, determining, device, discretion,
   disposition, enterprise, envisagement, estimate, estimation,
   evaluation, expectation, express intention, expressness, figure,
   figuring, footing, forecast, foresight, forethought, game, gauging,
   gingerliness, graphing, ground plan, guardedness, guidelines,
   hedge, hedging, heed, heedfulness, hesitation, idea,
   instrumentation, intention, intentionality, judiciousness, layout,
   lineup, long-range plan, mapping, master plan, measure,
   measurement, measuring, mensuration, method, methodology,
   metric system, mindfulness, operations research, organization,
   pawkiness, plan, planning, planning function, prearrangement,
   preconsideration, predeliberation, predetermination, prediction,
   premeditation, preresolution, prior consultation, procedure,
   product, program, program of action, prudence, prudentialness,
   quantification, quantization, rating, rationalization, reckoning,
   regardfulness, result, safeness, safety first, schedule, schema,
   schematism, schematization, scheme, scheme of arrangement, setup,
   slowness to act, solicitude, strategic plan, strategy, survey,
   surveying, system, systematization, tactical plan, tactics,
   telemetering, telemetry, tentativeness, the big picture,
   the picture, thoroughness, totaling, toting, triangulation,
   uncommunicativeness, unprecipitateness, valuation, wariness, way,
   working plan