zoom lensn. A camera lens whose focal length can be rapidly changed, allowing rapid change in the size of an image.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.zoom lens n (Photography) a lens system that allows the focal length of a camera lens to be varied continuously without altering the sharpness of the image. See also telephoto lens Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014zoom? lens` n. (in a camera or motion-picture projector) a lens assembly whose focal length can be continuously adjusted to provide various degrees of magnification with no loss of focus. [1935?40] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.