Liquid Crystal
A state of matter that flows like a liquid but retains some of the molecular ordering of a crystal.
Unit
Dimensionless
In depth
Liquid crystal phases are formed by elongated molecules that align along a common direction while remaining free to move. In the nematic phase only orientation is ordered; smectic phases add layering. Applying a small voltage reorients the molecules and changes how they rotate polarised light.
Examples in the real world
The twisted nematic layer in an LCD screen; cell membranes and some soap solutions behave as lyotropic liquid crystals.