철썩 + 부딪치다 (파도) / 때리다; 철썩철썩 · 철썩이다
splash, crash (waves on a shore); smack
Example
파도가 바위에 철썩 부딪쳤어요.
The waves crashed against the rocks with a splash.
Word parts
의성어 (sound word) for a big wave hitting something, or a hard slap. Its bright-vowel pair 찰싹 is a smaller, sharper slap or splash.
Good to know
Waves that keep crashing are 철썩철썩, or the verb 철썩이다: 파도가 철썩이는 소리.