1. the state or quality of being an opponent; opposition or antagonism
Usage: formal; less common than 'opposition'
2. in vision science, the property of color perception in which certain colors are perceived as mutually exclusive (e.g., red-green, yellow-blue)
Usage: technical; psychology and neuroscience

Examples

• The opponency between the two political parties made compromise difficult.
• Her opponency to the new policy was well documented in the meeting minutes.
• Color opponency explains why we cannot perceive a reddish-green or yellowish-blue.
• The researcher studied opponency in the visual cortex to understand color processing.
• Despite their opponency on most issues, they found common ground on education reform.