an early short-barreled pocket pistol.
Origin of derringer
1850–55, Americanism; named after Henry Deringer, mid-19th-century American gunsmith who invented it
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a short-barrelled pocket pistol of large calibre
Word Origin for derringer
C19: named after Henry Deringer, American gunsmith who invented it
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
1850, for Henry Deringer (1786-1868), U.S. gunsmith who invented it in the 1840s; prevailing misspelled form is how his name appeared on the many counterfeits and imitations. "A small pistol with a large bore, very effective at short range" [OED].
Online Etymology Dictionary, © 2010 Douglas Harper