To approximate is to calculate the value of something based on informed knowledge. A computer program can approximate the value of a house based on square footage, number of rooms, year built, and other relevant factors.

As a verb, approximate means "to estimate." Unlike the word guess, approximate implies the use of a logical or mathematical method. You might guess how tall a friend is based on the first number that comes to mind, but you could approximate his height by using your own height as a comparison. As an adjective, approximate can mean "near" or "close together." If your friend calls to say he’s at a location approximate to your house, she’s in your neighborhood.

Definitions of approximate
  1. adjective
    not quite exact or correct
    “the approximate time was 10 o'clock”
    synonyms: approximative, rough
    not exact
  2. adjective
    very close in resemblance
    “sketched in an approximate likeness”
    synonyms: near
    close in relevance or relationship
  3. adjective
    located close together
    approximate leaves grow together but are not united”
    synonyms: close together
    at or within a short distance in space or time or having elements near each other
  4. verb
    be close or similar
    “Her results approximate my own”
    synonyms: come close
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    approach, border on
    come near or verge on, resemble, come nearer in quality, or character
    approach a limit as the number of terms increases without limit
    type of:
    appear like; be similar or bear a likeness to
  5. verb
    judge tentatively or form an estimate of (quantities or time)
    synonyms: estimate, gauge, guess, judge
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    quantise, quantize
    approximate (a signal varying continuously in amplitude) by one whose amplitude is restricted to a prescribed set of discrete values
    gauge something incorrectly or improperly
    place, put, set
    estimate the duration or outcome of something
    lowball, underestimate
    make a deliberately low estimate
    estimate the value of (property) for taxation
    calculate as being
    count, reckon
    take account of
    approximate by ignoring all terms beyond a chosen one
    estimate based on a calculation
    type of:
    calculate, cipher, compute, cypher, figure, reckon, work out
    make a mathematical calculation or computation
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