Jackson considers adjectives for his hyung every time he sees him, but he can never figure out the right one. Hyper isn't right; he's not always a ball of energy. Cute just doesn't sound right, that's something he associates more with BamBam, anyway. His brain is full of adjectives, but he just doesn't know which one is best, until a conversation with insightful leader Jaebum leads him to discover it. 

(And this is why he respects Jaebum as his leader. The man is all-knowing. That is his adjective.)