The word 嚎啕大哭 is formed by combining the two-character term 嚎啕, where both characters independently convey the meaning of wailing or sobbing, with the two-character phrase 大哭, in which 大 (loudly) modifies 哭 (to cry). The pair 嚎啕 acts as an intensifying reduplication, and its coupling with 大哭 creates a compounded structure that emphasizes vehement, loud crying through semantic reinforcement.