The act of opposing or resisting. 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\u201d ( Virginia Woolf). Placement opposite to or in contrast with another. Something that serves as an obstacle. A political party or an organized group opposed to the group, party, or government in power. Astronomy The position of two celestial bodies when their longitude differs by 180\u00b0, especially a configuration in which Earth lies on a straight line between the sun and a superior planet or the moon. Astronomy The position of the superior planet or the moon in this configuration. Logic The relation existing between two propositions having an identical subject and predicate but differing in quantity, quality, or both. Linguistics Contrast in a language between two phonemes or other linguistically important elements.