Turning or rotating the plane of polarization of light towards the left; -- applied to crystals and compounds exhibiting optical activity, such as levulose, left-handed quartz crystals, etc. Opposite of dextrorotatory.

Describes compounds that rotate plane-polarized light to the left (counterclockwise) when viewed in the direction of the light source. See dextrorotatory.

Compare with dextrorotatory. Having the property of rotating plane-polarized light counterclockwise.