The word "伪证" is formed by combining the character "伪", meaning false or forged, which consists of the radical "亻" (person) and the component "为" (to do), with the character "证", meaning evidence or testimony, which consists of the radical "讠" (speech) and the component "正" (correct). In this compound, "伪" directly modifies "证" to specify that the evidence or testimony is false, resulting in the meaning of perjury or false testimony.