conk

2
[kongk, kawngk]
verb (used without object) Slang.
  1. to break or fail, as a machine or engine (often followed by out): The engine conked out halfway there.
  2. to slow down or stop; lose energy (often followed by out).
  3. to go to sleep (usually followed by off or out).
  4. to lose consciousness; faint (usually followed by out).
  5. to die (usually followed by out).

Origin of conk

2
First recorded in 1915–20; perhaps of imitative orig.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for conk off

conk

verb
  1. to strike (someone) a blow, esp on the head or nose
noun
  1. a punch or blow, esp on the head or nose
  2. the head or (esp Brit and NZ) the nose

Word Origin for conk

C19: probably changed from conch
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 conk off

conk

v.

as in conk out, 1918, coined by World War I airmen, perhaps in imitation of the sound of a stalling motor, reinforced by conk (v.) "hit on the head," originally "punch in the nose" (1821), from conk (n.), slang for "nose" (1812), perhaps from fancied resemblance to a conch (pronounced "conk") shell.

Online Etymology Dictionary, © 2010 Douglas Harper