noun, plural du·fus·es.
noun, plural doo·fus·es.
Slang. a foolish or inept person.
Origin of doofus
1960–65, Americanism; probably alteration of earlier goofus in same sense
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
informal, mainly US a slow-witted or stupid person
Word Origin for doofus
C20: from Black slang
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
student slang, "dolt, idiot, nerd," by 1960s. "Dictionary of American Slang" says "probably related to doo-doo and goofus."
Online Etymology Dictionary, © 2010 Douglas Harper