2 definitions by Fellow K-pop Stan, helping.

The K-POP group ITZY, has a fandom. ITZY consists of 5 members.
Hwang Yeji (Yeji)
Choi Jisu (Lia)
Shin Ryujin (Ryujin)
Lee Chaeryeong (Chaeryeong)
Shin Yuna (Yuna).

At July 8 midnight KST, ITZY announced a their fandom name; MIDZY. ITZY explained that MIDZY meant trust. They chose it because they want to show their fandom that they trust each other.

Korean: 믿어
Pronounced as: Mid-tsi or Mid-tzi
Meaning: Trust
(Midzy is not really used in a sentence, as it is a fandom name.)
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According to Hwang Yeji from the K-pop group, ITZY, addractive means attractive+addictive. This is what you apparently call a "Yeji Word".

Origin:

Yeji said: Because we are so ADDRACTIVE.

Her member, Ryujin said it is ATTRACTIVE, Yeji said it wasn't a mistake. She calls it a "Yeji Word".
"Because we are so ADDRACTIVE" - Hwang Yeji, 2021
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