白痴 (simplified, jyutping baak6 ci1, traditional 白癡)
Derived terms 
From Middle Chinese.
白痴 (hiragana はくち, romaji hakuchi)
- idiocy, imbecility
- (dated, medicine) profound mental retardation, indicating an IQ of under 25
- an idiot, an imbecile
- (dated, medicine) a person suffering from profound mental retardation, with an IQ of under 25
Usage notes 
No longer used in the clinical sense, much as English idiot is no longer used clinically.
See also 
白痴 (simplified, Pinyin báichī, traditional 白癡)