opponent /ə-pōˈnənt/

1. The person opposed to one in a contest, struggle, battle, etc
2. Someone who opposes a course of action, belief, etc
3. An opponent muscle (anatomy)

1. Opposing
2. Antagonistic (with to; formerly with with)
3. Placed opposite or in front
4. (of a muscle) opposing one part (eg a digit) to another (anatomy)

oppoˈnency noun

• invalidate
• invalidated
• invalidates
• invalidating
• invalidation
• invalidations
• invalided
• invalidhood
• invalidhoods
• invaliding
• invalidings
• invalidism
• invalidisms
• invalidities
• invalidity
• invalidly
• invalidness
• invalidnesses
• invalids
• invaluable
• invaluableness
• invaluably
• Invar
• invariabilities
• invariability