a Chinese verse form that was popular during the Tang dynasty (618–907). An outgrowth of the lü-shih (Pinyin lüshi), it is a four-line poem, each line of which consists of five or seven words; it omits either the first four lines, the last four lines, the first two and the last two lines, or the middle four lines of the lü-shih. Thus, it retains the tonal quality of the lü-shih, but the antithetical structure is optional. Much like the Persian robai (robāʿī) and the Japanese haiku, chüeh-chü are judged by suggestiveness and economy.