海水
hǎishuǐ · HSK 4
seawater
🌊 海水 = 海 (sea) + 水 (water) — literally sea-water
A transparent compound: 海 (hǎi, sea) plus 水 (shuǐ, water). The 氵 radical on the left of 海 is itself a compressed form of 水, so the whole word is essentially water-water-of-the-sea.
海 — water radical 氵 + 每 (phonetic)
海 is a phono-semantic compound. The 氵 (water) radical signals the meaning—a vast body of water—while 每 supplies the sound. Originally referring to the sea or ocean, it later extended figuratively to mean 'vast' or 'a great quantity,' as in 人海 (a sea of people).
水 — pictograph of flowing water
水 is a pictograph depicting a stream of flowing water, with the central line representing the main current and the side strokes showing splashing droplets or ripples. In oracle bone script it was drawn even more clearly as a wavy vertical line with branches. It retains its original meaning of 'water' and also serves as a radical, often appearing in the compressed form 氵.