the.com/adversary
The nemesis you never asked for but somehow earned.
means An opponent or enemy actively working against you in conflict, competition, or argument.
from From Latin adversarius, meaning turned toward you, from adversus — literally one standing in your face, opposing you head-on.
Legal termCourts call opposing parties the adversary system.
Religious weightSatan literally means adversary in Hebrew.
Cyber usageSecurity pros call hackers threat adversaries.