1. A belief or conclusion held with confidence but not substantiated by positive knowledge or proof: "The world is not run by thought, nor by imagination, but by opinion" (Elizabeth Drew). See Synonyms at view.
2. A judgment based on special knowledge and given by an expert: a medical opinion.
3. A judgment or estimation of the merit of a person or thing: has a low opinion of braggarts.
4. The prevailing view: public opinion.
a. A court's formal, usually written statement explaining its reasons for its decision in a case.
b. An attorney's formal, usually written statement giving an assessment of how the law should be or is likely to be applied in a particular situation.
c. A piece of testimony that is not usually admissible when given by a layperson, as in contrast to an opinion given by an expert witness.
[Middle English, from Old French, from Latin opīniō, opīniōn-, from opīnārī, to think.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.