levorotation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A counterclockwise rotation, especially of the plane of polarized light.

from The Century Dictionary.

• The rotation of the plane of polarization of light toward the left.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physics & Chem.) Rotation in the direction of an outgoing right-handed screw; counter-clockwise rotation; -- applied chiefly to the turning of the plane of polarization of light.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Rotation in an anticlockwise direction, especially such rotation of the plane of polarized light.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun rotation to the left