magnification

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

• noun The act of magnifying or the state of being magnified.
• noun The process of enlarging the size of something, as an optical image.
• noun Something that has been magnified; an enlarged representation, image, or model.
• noun The ratio of the size of an image to the size of an object.

from The Century Dictionary.

• noun The act of magnifying, or the state of being magnified or enlarged, as by a lens.
• noun In microscopy, specifically, increase of visual power in respect of penetration as well as superficial enlargement, thus contrasting with amplification.
• noun The act of magnifying or extolling.
• noun In the theory of optical images, the ratio f/x or x′ /f′ , where f is the focal length of the object-space of the optical system and x the distance of the object from the principal focal plane of that space, or where f′ and x′ are the corresponding quantities in the image-space.
• noun In mathematics, in conformal representation, the modulus of the derivative

from the GNU version of the Collaborative International Dictionary of English.

• noun rare The act of magnifying; enlargement; exaggeration.

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

• noun The act of magnifying; enlargement; exaggeration.
• noun The apparent enlargement of an object in an image.

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

• noun making to seem more important than it really is
• noun the ratio of the size of an image to the size of the object
• noun a photographic print that has been enlarged
• noun the act of expanding something in apparent size