X0

X0 may refer to:

Grammar

 * X0, denoting a sentence component
 * Zero-level projection, in X-bar theory
 * Head (linguistics), or nucleus

Science, technology and mathematics

 * SpaceShipOne flight 15P, a 2004 private spaceflight
 * X/0, division by zero
 * Turner syndrome, a disorder in which all or part of an X chromosome is absent
 * X0 sex-determination system, as found in some insects

Vehicles

 * X0, a smaller rigged version of an X1 (dinghy)
 * X0, running number for N700 Series Shinkansen prototype from 2014 to 2021