standard errorn. A generalized notion of standard deviation, used to characterize the dispersion of a statistic (such as the sample mean) calculated from randomly sampled data.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.standard error n (Statistics) statistics the estimated standard deviation of a parameter, the value of which is not known exactly Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014