NSW Opportunity Class
Adversary
noun/AD-vuhr-suh-ree/
An enemy or opponent who is against you in a contest or fight.
In contextThe two schools have long been sporting adversaries on the footy field.
Remember it
Adversary has 'adverse' (against) — an adversary is the one turned against you.
Use it well
Use for a serious opponent in a struggle; more formal than plain 'enemy'.