archnemesis
noun
arch·nem·e·sis
| \ (ˌ)ärch-ˈne-mə-səs
\
\
plural archnemeses\ (ˌ)ärch-ˈne-mə-ˌsēz
\
\
Definition of archnemesis
: archrival
Ratchet and Clank are split up after the spritelike beings called the Zoni whisk Clank away. Players soon find out Dr. Nefarious, their archnemesis, was partly behind the kidnapping. — Gieson Cacho, Contra Costa Times (California), 10 Dec. 2009
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