<p><strong>Noun</strong></p><ul><li>the action of opposing, resisting, or combating</li><li>antagonism or hostility</li><li>a person or group of people opposing, criticizing, or protesting something, someone, or another group</li><li>the major political party opposed to the party in power and seeking to replace it</li><li>the act of placing opposite, or the state or position of being placed opposite</li><li>the act of opposing, or the state of being opposed by way of comparison or contrast</li></ul><p><strong>Logic</strong></p><ul><li>the relation between two propositions that have the same subject and predicate, but which differ in quantity or quality, or in both</li><li>the relation between two propositions in virtue of which the truth or falsity of one of them determines the truth or falsity of the other</li></ul><p><strong>Astronomy</strong></p><ul><li>the situation of two heavenly bodies when their longitudes or right ascensions differ by 180°</li></ul><p><strong>Astrology</strong></p><ul><li>the situation of two heavenly bodies or groups of heavenly bodies whose celestial longitudes differ by 180°, conducive to confrontation or revelation</li></ul><p><strong>Electricity</strong></p><ul><li>the condition that exists when two waves of the same frequency are out of phase by one-half of a period</li></ul><p><strong>Linguistics</strong></p><ul><li>the relationship between any two alternative units within a linguistic system, especially between minimally distinct phonemes</li><li>the feature that constitutes the difference between two such units</li></ul>