아니잖소

is not, isn't (you know)

→ 아니다
아니 not be + 잖 Reminder / shared knowledge + 소 Formal polite declarative
adjective Rare #19,082
is not, isn't (you know) The ending -소 sounds old-fashioned and is mainly heard in historical or dramatic speech.
KO: 그건 내 일이 아니잖소.
EN: That isn't my job, you know.
Forms of 아니다

당신은 토르플릿 사람이 아니잖소.

You’re not from Torflit, are you?

빵 만드는 일이 아니잖소

It’s not like we’re making bread.

— 붉은 돼지 (1992)

당신 아들도 아니잖소

He's not even your son.

— 해리 포터와 불사조 기사단 (2007)