The word 勾心斗角 is formed by combining four characters: 勾 (hook), 心 (heart), 斗 (fight), and 角 (horn). It derives from traditional Chinese architecture, where 勾心 refers to the interlocking of beams and rafters that hook into the central core, and 斗角 describes the upward-curving eaves that resemble clashing horns. This concrete architectural term was later extended to metaphorically represent people engaging in intricate scheming and covert rivalry.