The act, process, or result of approximating.(noun)
Mathematics An inexact result adequate for a given purpose.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "approximation" in a sentence
"So, a reasonable approximation is that oil prices should be expected to go up at the interest rate."
"In early 20th century, with advances in approximation theory, spline functions were beginning to emerge."
"Provided the approximation is done with enough significant digits, the numerator of the Bernoulli number is a mere integer part of the product."