専せん門もんバカ

せ

ん

も

ん

ば

か

Meanings

noun

person ignorant outside their specialty; overspecialized person; one-trick pony

Derogatory term for someone deeply knowledgeable in one narrow area but clueless about everything else. Often used critically or self-deprecatingly.

彼かれは数すう学がくの専せん門もんバカで、簡かん単たんな家か事じもできない

。

He's a math specialist who is ignorant of everything else; he can't even do simple housework.

専せん門もんバカにならないように、幅はば広ひろい知ち識しきを身みにつけたい。

I want to acquire broad knowledge so I don't become a one-trick pony.

Kanji

専specialty, exclusive, mainly
門gate, counter for cannons
馬horse
鹿deer

Related words

専せん門もん家か
専門家 is a neutral term for an expert or specialist, while 専門バカ is derogatory, implying narrow-mindedness and ignorance outside one's field.
オタク
オタク refers to a geek or enthusiast, often with obsessive interest, but not necessarily lacking general knowledge. 専門バカ specifically criticizes overspecialization and ignorance of other areas.

Written forms

専せん門もんバカ
Common mixed kanji-katakana spelling. バカ is often written in katakana for emphasis or clarity.
専せん門もん馬ば鹿か
Full kanji spelling, less common but still seen.

Etymology

Compound of 専門 (specialty) and バカ (fool). The exact origin is uncertain, but it likely arose as a colloquial criticism of academics or professionals with narrow expertise.