The term 堂弟 (tángdì) is a compound word formed through the combination of two meaningful characters: 堂 (táng), which historically denotes the main hall of a family and, by extension, signifies a paternal lineage or shared surname, and 弟 (dì), meaning younger brother. Together, they specifically refer to a younger male cousin on the paternal side, as the "堂" prefix distinguishes him as the son of one's father's brother, thereby placing him within the same patriarchal clan, in contrast to maternal cousins who use the prefix "表" (biǎo).