응결이 · 응결을
condensation
Example
수증기의 응결로 하늘에 구름이 만들어집니다.
Clouds form in the sky through the condensation of water vapor.
Word parts
응 congeal+결 bind
Literally 'congeal and bind together'.
Good to know
응결 is gas to liquid (condensation); 응고 is liquid to solid — don't mix them up.