専せん

noun, used as a suffix

exclusively doing ...; person who exclusively does ...; fetish for ...; someone with a fetish for ...

Slang suffix attached to nouns or noun-like stems. Indicates that someone is obsessed with or exclusively devoted to the thing. Often used in otaku or internet subcultures.

• 彼かれはゲーム専せんで、他ほかのことには興きょう味みがない。

  He's exclusively into games and has no interest in anything else.

• あの人ひとは猫ねこ専せんだから、猫ねこカフェに毎まい日にち行いくらしい。

  That person has a cat fetish, so I hear they go to a cat café every day.

noun

first; most important thing; number one priority

Obsolete noun meaning the foremost or most important thing. Not used in modern Japanese outside of historical contexts.

• 古ふるい文ぶん献けんでは、専せんを決きめることが大だい事じだと書かかれている。

  In old documents, it is written that deciding what is most important is crucial.