専せん門もん分ぶん野や

noun

area of expertise; specialty; field

Refers to a person's specialized field of study, work, or knowledge.

• 彼かれの専せん門もん分ぶん野やは物ぶつ理り学がくです。

  His area of expertise is physics.

• 専せん門もん分ぶん野やについての質しつ問もんに答こたえる。

  Answer questions about one's field of expertise.