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
See also XO (disambiguation) X00, a popular DOS-based FOSSIL driver which was commonly used in the mid 1980s to the late 1990s 0X (disambiguation)