adversary
US /ˈæd.vɚ.ser.i/
UK /ˈæd.vɚ.ser.i/

1.
adversario, oponente
one's opponent in a contest, conflict, or dispute
:
•
He faced his old adversary in the final round.
Se enfrentó a su antiguo adversario en la ronda final.
•
The two nations have been adversaries for centuries.
Las dos naciones han sido adversarias durante siglos.