Xo Definition

abbreviation
Executive officer.
Webster's New World
XO is defined as hugs and kisses, or is the abbreviation for a military executive officer.
An example of XO is what someone would put at the end of an email to a good friend, before signing their name.
An example of XO is the individual on a Navy ship who is the primary assistant to the commanding officer and who is typically responsible for the administrative actions of the ship.
YourDictionary

Alternative form of xoxo. (an abbreviation for hugs and kisses, usually placed at the end of a letter.)

Wiktionary
other

The abbreviation for crystal oscillator. See crystal oscillator.

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