saturation (n.)youdaoicibaDictYouDict[saturation 词源字典]
1550s, formed in English from saturate, or else from Late Latin saturationem (nominative saturatio), noun of action from past participle stem of saturare. Saturation bombing is from 1942, first in reference to Allied air raid on Cologne, Germany.[saturation etymology, saturation origin, 英语词源]