洲

Phono-semantic compound:

Water radical (水) provides the meaning “related to water.”

州 (고을 주) provides the sound.

Together, the character conveys the sense of land within water, formed by sediment deposits.

三角洲 (삼각주) — delta (land at the mouth of a river).

洲渚 (주저) — islets and sandbanks.

亞洲 (아주) — Asia (lit. “eastern continent”).

歐洲 (구주) — Europe.

A common morpheme in modern place names, especially for continents (洲 = “continent” in modern usage).

Distinction: 洲 = islet/sandbank or continent; 島 = sea island.