This is the 12102nd most frequent Korean word.
누굴
"누굴" is the contracted form of "누구를," meaning "whom" (object form).
The word '누굴' is derived from '누구를', which is the accusative form of '누구' (meaning 'who'). In this sentence, '누굴' is used to ask whom the subject is going to meet.
누굴 만나러 가는 거야?
Who are you going to see?
Here, '누굴' is again used as the accusative form of '누구', questioning the object of the verb 'looking for'.
그는 누굴 찾고 있었던 거야?
Who was he looking for?
'누굴' indicates inquiry about the person who was seen at the party, serving as the object of the verb 'seen'.