the officer second in command of a military or naval organization.
an officer charged with executive duties, as in a corporation.
Origin of executive officer
First recorded in 1780–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for executive officer
the second-in-command of any of certain military unitsAbbreviation: (US) XO
a specialist seaman officer, responsible under the captain for the routine efficient running of the ship in the US, British (formerly), and certain other navies
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