a. The act of opposing or resisting.
b. The condition of being in conflict; antagonism: "The history of men's opposition to women's emancipation is more interesting perhaps than the story of that emancipation itself" (Virginia Woolf).
2. Placement opposite to or in contrast with another.
3. Something that serves as an obstacle.
4. often Opposition A political party or an organized group opposed to the group, party, or government in power.
a. The position of two celestial objects when their longitude differs by 180°, especially a configuration in which the sun and a superior planet or the moon are on opposite sides of Earth.
b. The position of the superior planet or the moon in this configuration.
6. Logic The relation existing between two propositions having an identical subject and predicate but differing in quantity, quality, or both.
7. Linguistics Contrast in a language between two phonemes or other linguistically important elements.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.