1. What does it mean?
안읽씹 combines 안 읽다, not reading, with 씹다 in the slang sense of ignoring. It contrasts with 읽씹, where the message has been marked as read but receives no reply.
Also written or said as 안 읽씹, 안읽씹하다, anilkssip
2. The nuance
This label can imply intention, but an unread indicator alone cannot establish it. The recipient might be busy or may have seen a notification preview. Do not treat the word as evidence of rejection or a relationship ending.
3. Examples
“답이 없어서 안읽씹인 줄 알았는데 휴대폰을 집에 두고 나왔대.”
I thought they were leaving me on unread, but they had left their phone at home.
“바쁠 때는 안읽씹으로 보일 수 있으니 나중에 답한다고 적어 둬.”
When you're busy it might look like you're ignoring the message, so say you'll reply later.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.