accurate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Conforming exactly to fact; errorless.
• adjective Deviating only slightly or within acceptable limits from a standard.
• adjective Capable of providing a correct reading or measurement.
• adjective Acting or performing with care and precision; meticulous.

from The Century Dictionary.

• Characterized by extreme care; hence, in exact conformity to truth, or to a standard or rule, or to a model; free from error or defect; exact: as, an accurate account; accurate measure; an accurate expression; an accurate calculator or observer.
• Determinate; precisely fixed.
• Synonyms Accurate, Correct, Exact, Precise, Nice, careful, particular, true, faithful, strict, painstaking, unerring. Of these words correct is the feeblest; it is barely more than not faulty, as tested by some standard or rule. Accurate implies careful and successful endeavor to be correct: as, an accurate accountant, and, by extension of the meaning, accurate accounts; an accurate likeness. Exact is stronger, carrying the accuracy down to minute details: as, an exact likeness. It is more commonly used of things, while precise is used of persons: as, the exact truth; he is very precise in his ways. Precise may represent an excess of nicety, but exact and accurate rarely do so: as, she is prim and precise. As applied more specifically to the processes and results of thought and investigation, exact means absolutely true; accurate, up to a limited standard of truth; precise, as closely true as the utmost care will secure. Thus, the exact ratio of the circumference to the diameter cannot be stated, but the value 3.14159265 is accurate to eight places of decimals, which is sufficiently precise for the most refined measurements. Nice emphasizes the attention paid to minute and delicate points, often in a disparaging sense: as, he is more nice than wise.

from the GNU version of the Collaborative International Dictionary of English.

• adjective In exact or careful conformity to truth, or to some standard of requirement, the result of care or pains; free from failure, error, or defect; exact
• adjective obsolete Precisely fixed; executed with care; careful.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective In exact or careful conformity to truth; the result of care or pains; free from failure, error, or defect; exact; as, an accurate calculator; an accurate measure; accurate expression, knowledge, etc.
• adjective Deviating only slightly or within acceptable limits.
• adjective obsolete Precisely fixed; executed with care; careful.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective (of ideas, images, representations, expressions) characterized by perfect conformity to fact or truth ; strictly correct
• adjective conforming exactly or almost exactly to fact or to a standard or performing with total accuracy