[a traditional method of indicating the pronunciation of a Chinese character by using two other Chinese characters，the first having the same consonant as the given character and the second having the same vowel (with or without final nasal) and tone] 古汉语注音方法，用两个字注读另一个字，例如“塑，桑故切(或桑故反)”。被切字的声母跟反切上字相同(“塑”字声母跟“桑”字声母相同，都是s)，被切字的韵母和字调跟反切下字相同(“塑”字的韵母的字调跟“故”相同，都是u韵母，都是去声)
