magnitude

(noun) the property of relative size or extent (whether large or small). Examples: "They tried to predict the magnitude of the explosion." "About the magnitude of a small pea."

(noun) a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10. Synonyms: order of magnitude.

(noun) relative importance. Example: "A problem of the first magnitude."