Synonyms for Approximation:
n.
computational, abacus, decimal place, countdown, average, deviation, binomial. match, carbon copy, conjecture, double, parallel, echo, mirror image, clone, equivalent. precise. •approximation (noun)bringing close together, idea, estimation, estimate.
•calculation (noun)
arithmetic, measurement, total, conclusion, consideration, statistics, thought, program, multiplication, method, calculus, plan, deduction, inference, tally, computation, study, valuation, plot, triangulation, scheme, sum, supposition, account, schedule, evaluation, assessment, algorithm, calculation, appraisal, value, rank, determination, presumption, system, judgement, reckoning, estimation, quantification, mathematics, count, division, gauge, guess, enumeration, score, algebra.
•closeness (noun)
likeness.
•cognition (noun)
estimate, estimation, idea.
•estimate (noun)
conjecture, estimation, guess.
•imprecision (noun)
inexactness, inaccurateness, inexactitude, inaccuracy, imprecision.
•representation (noun)
facsimile, duplication, likeness, replica, statue, drawing, cartoon, model, portrayal, carving, imitation, impression, outline, rendering, analogy, figurine, illustration, snapshot, picture, photograph, miniature, pastiche, idol, representation, cast, copy, effigy, metaphor, image, depiction, bust, silhouette.
Other synonyms:
deviation, abacus, binomial, carbon copy, decimal place, computational, mirror image, average, countdown. clone, equivalent, match. echo. parallel. double. •Other relevant words:
binomial, computational, double, average, deviation, precise, bringing close together, equivalent, match, abacus, parallel, idea, conjecture, estimate, clone, echo, countdown.
Usage examples for approximation

Can we make any approximation to axiomatical truth for ourselves? – History of American Socialisms by John Humphrey Noyes