XO

XO may refer to:

Executive officer (military)
XO grade of cognac, where the youngest brandy is at least 7 years old.
XO is the IATA code for LTE International Airways
Crystal oscillator
The Xbox 360 (The O looks like a circle 360°)
Tic-tac-toe (a game)
Eastern Orthodoxy (Christianity), from the Greek: Xristianos Orthodoksos (Χριστιανός Ορθόδοξος)
Crossover track
XO Communications, a telecom company
Kisses (X) and hugs (O), a common closing to a letter (often a love letter). Repetition can be used to convey intensity (e.g. "xoxoxoxoxo").
An incorrect notation (It should be X0 with a zero, not an O) for denoting the sex chromosomes of an individual with Turner syndrome
Badtz-Maru, a character from Sanrio's Hello Kitty series
The album XO by Elliott Smith.