absolute value

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

• noun The numerical value of a real number without regard to its sign. For example, the absolute value of −4 (written |-4|) is 4.
• noun The modulus of a complex number, equal to the square root of the sum of the squares of the real and imaginary components of the number.

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

• noun mathematics For a real number, its numerical value without regard to its sign; formally, -1 times the number if the number is negative, and the number unmodified if it is zero or positive; the distance of a quantity from zero on a number line.
• noun mathematics For a complex number, the square root of the sum of the squares of its real and imaginary parts.

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

• noun a real number regardless of its sign