X
- X (charge)Quantum number associated with certain grand unification theories
- X-rayForm of electromagnetic radiation
- X-ray crystallographyTechnique used for determining crystal structures and identifying mineral compounds
- X11 color namesIn computing, on the X Window System, X11 color names are represented in a simple text fil
- Xenia de la OssaXenia de la Ossa Osegueda (born 30 June 1958, San José, Costa Rica) is a theoretical physi
- Xi baryonThe Xi baryons or cascade particles are a family of subatomic hadron particles which have
- Xie ChenChinese physicist