British Dictionary definitions for significant figures
significant figures
plural noun
1.
the figures of a number that express a magnitude to a specified degree of accuracy, rounding up or down the final figure: 3.141 59 to four significant figures is 3.142
2.
the number of such figures: 3.142 has four significant figures Compare decimal place (sense 2)
(sĭg-nĭf'ĭ-kənt) The digits in a decimal number that are warranted by the accuracy of the means of measurement. Significant digits are all the numbers beginning with the leftmost nonzero digit, or beginning with the first digit after the decimal point if there are no nonzero digits to the left of the decimal point, and extending to the right. For example, 302, 3.20, and 0.023 all have three significant digits.