過密
かみつ · kamitsu · JLPT N1 · noun
crowded
🚇 過 = too much + 密 = dense, so 過密 = too dense = crowded
過 means excess or going beyond, and 密 means dense or tight. Together they describe a space packed past its normal limit, such as a crowded train or city.
密 — 宀 roof + 必 (phonetic) + 山 mountain
Originally referring to a hidden, sheltered place in the mountains, 密 combines 宀 (roof/cover) over 必 (phonetic) with 山 (mountain) at the base. The meaning extended from 'secluded mountain hideaway' to 'dense, close, secret'. Today it commonly means dense, intimate, or secret.