noun
throughout the afternoon; all afternoon
Refers to the entire duration of the afternoon, often implying continuity or persistence.
彼は午後中ずっと会議に出ていた。
He was in meetings all afternoon.
午後中雨が降り続いた。
It kept raining throughout the afternoon.
一日中 means 'all day long', covering both morning and afternoon, whereas 午後中 is limited to the afternoon.
Compound of 午後 (gogo, 'afternoon') and 中 (chū, 'throughout'). The reading じゅう is a rendaku form of ちゅう used when meaning 'throughout a period of time'.