A liquid crystal compound and a liquid crystal medium are described. The liquid crystal compound is stable to heat and light and has a large dielectric anisotropy and a large optical anisotropy. The liquid crystal medium has a wide temperature range of liquid crystal phase, a large optical anisotropy and a large dielectric anisotropy, and exhibits an optically isotropic liquid crystal phase. The liquid crystal compound has 4 or 5 benzene rings, one of which is a chlorofluorobenzene ring. The liquid crystal medium is characterized in containing the liquid crystal compound and a chiral dopant and exhibiting an optically isotropic liquid crystal phase.