[verb ges-tuh-meyt; noun ges-tuh-mit, -meyt]Informal.
- to estimate without substantial basis in facts or statistics.
- an estimate arrived at by guesswork.
Origin of guesstimate
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- an estimate calculated mainly or only by guesswork
- to form a guesstimate of
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for guesstimate
Online Etymology Dictionary, © 2010 Douglas Harper