洞

Phono-semantic compound:

氵(水, 물 수) — semantic, “water.”

同 (한 가지 동) — phonetic, also suggesting “togetherness.”

Originally referred to “a hollow place where water gathers,” hence “cave, hollow.” By extension: village (where people gather together), and figuratively “to penetrate, to understand clearly.”

Meanings split between 동 (cave, village, hollow) and 통 (to penetrate, perceive).

Still common in Korean place names (동네 “neighborhood”), in classical compounds (通達, 洞察), and in everyday words like 洞窟 “cave.”

공동 (空洞) — cavity, hollow, void

대동 (大洞) — Daedong (place name; also “large village”)

동굴 (洞窟) — cave, grotto

동내 (洞內) — inside a village/neighborhood

동내방내 (洞內坊內) — throughout the village, everywhere in town

동리 (洞里) — neighborhood, hamlet

동문 (洞門) — cave entrance, village gate

동방 (洞房) — bridal chamber; inner chamber

동장 (洞長) — village head

통견 (洞見) — clear insight

통달 (洞達) — thorough understanding

통찰 (洞察) — keen observation, penetration

통촉 (洞燭) — clear discernment