le·vo·ro·ta·to·ry (lē′və-rōtə-tôr′ē) also le·vo·ro·ta·ry (-tə-rē)
adj. Symbol l-
Of or relating to an optically active substance that rotates the plane of polarized light to the left, or counterclockwise (when looking toward the light source): Only levorotatory amino acids are biologically active.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.