1) Contrariness, wordwise 2) Semantic relation 
semantic contrasts.
(from the article `language`) It has been maintained that the human brain has a preference for binary oppositions, or polarities. If this is so, it will help explain the numerous ...
Semantic contrasts.
[n] - the semantic relation that holds between two words that can (in a given context) express opposite meanings
antonymy 1. The semantic relation that holds between two words that can (in a given context) express opposite meanings. 2. The relationship between lexical items that are binary opposites in meaning (example: alive and dead), gradable opposites in meaning (example: young and old), or converse opposites (example: buy and sell).
noun the semantic relation that holds between two words that can (in a given context) express opposite meanings