Provided is a liquid crystal compound satisfying at least one of physical properties such as high stability to heat and light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound, represented by formula (1):

##STR00001##

wherein, in formula (1), R.sup.1 is alkoxy having 1 to 9 carbons or the like; R.sup.2 is alkenyl having 2 to 10 carbons; Z.sup.1 and Z.sup.2 are independently a single bond, —CH.sub.2CH.sub.2—, —CH═CH— or the like; and a and b are independently 0 or 1.

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy and large dielectric anisotropy, or the liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device including the composition. The liquid crystal composition contains a specific compound having small optical anisotropy as a first component, and a specific compound having positive dielectric anisotropy as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.

Provided is a liquid crystal compound satisfying at least one of physical properties such as high stability to heat and light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A compound, represented by formula (1): ##STR00001##
wherein, in formula (1), R.sup.1 is alkoxy having 1 to 9 carbons or the like; R.sup.2 is alkenyl having 2 to 10 carbons; Z.sup.1 and Z.sup.2 are independently a single bond, CH.sub.2CH.sub.2, CHCH or the like; and a and b are independently 0 or 1.

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy and large dielectric anisotropy, or the liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device including the composition. The liquid crystal composition contains a specific compound having small optical anisotropy as a first component, and a specific compound having positive dielectric anisotropy as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.