A liquid-crystal composition and a liquid-crystal display device employing the liquid-crystal composition are provided. The liquid-crystal composition includes a first component and a second component. The first component includes one or more compounds represented by Formula (I), and the second component includes one or more compounds represented by Formula (II):

##STR00001## wherein R1, R2, A1, A2, A3, A4, Z1, Z2, Z3, m, m, n, and n are defined as in the specification.

A liquid crystal compound and a composition employing the same are provided. The liquid crystal compound has a structure represented by Formula (I) ##STR00001## wherein R1, A1, A2, A3, A4, Z1, Z2, Z3, Z4, X, m, n, o, and p are defined as in the description.

A liquid crystal compound is described, having a large dielectric anisotropy, a high voltage holding ratio and stability to heat, light and so forth, maintaining a nematic phase in a wide temperature range, and having a suitable optical anisotropy and an excellent compatibility with other liquid crystal compounds. Particularly, a liquid crystal compound having a large dielectric anisotropy is described. The compound is represented by formula (1): ##STR00001##
In the formula, for example, R.sup.1 is alkyl having 1 to 20 carbons; ring A.sup.1, ring A.sup.2, ring A.sup.3, ring A.sup.4, ring A.sup.5 and ring A.sup.6 are independently 1,4-cyclohexylene or 1,4-phenylene; Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4, Z.sup.5, Z.sup.6 and Z.sup.7 are independently a single bond, (CH.sub.2).sub.2, COO, OCO, CF.sub.2O, OCF.sub.2 or CHCH; X.sup.1 is fluorine, CF.sub.3 or OCF.sub.3; and Y.sup.1 and Y.sup.2 are independently hydrogen or fluorine.

Liquid-crystal compounds, liquid-crystal compositions, and liquid-crystal devices employing the same are provided. The liquid-crystal compound has a structure of Formula (I): ##STR00001##
wherein R.sup.1 is hydrogen, C.sub.1-10 alkyl, or C.sub.2-10 alkenyl; R.sup.2 is, C.sub.2-10 alkenyl, or C.sub.2-10 fluoroalkenyl, in which one or two nonadjacent CH.sub.2 is replaced by O, or C.sub.2-10 ether; A.sup.1, A.sup.2, A.sup.3, and A.sup.4 are independently ##STR00002##
R.sup.3 is independently hydrogen, or halogen; Z.sup.1, Z.sup.2, and Z.sup.3 are independently single bond, CH.sub.2, (CH.sub.2).sub.2, (CH.sub.2).sub.4, CH.sub.2O, OCH.sub.2, CFCF, (CH.sub.2).sub.2CF.sub.2O, (CH.sub.2).sub.2OCF.sub.2, OCF.sub.2(CH.sub.2).sub.2, CF.sub.2O(CH.sub.2).sub.2, COO, OCO, CF.sub.2O, OCF.sub.2, CC, CHCH, CHCH(CH.sub.2).sub.2, or (CH.sub.2).sub.2CHCH; and n and m are independently 1 or 0.