红豆 (hóngdòu) literally means 'red bean' and refers specifically to the small, reddish-brown adzuki bean (Vigna angularis), a legume widely used in East Asian cuisine and traditional medicine. The character 红 (hóng) means 'red', describing its distinctive color, while 豆 (dòu) means 'bean' or 'legume', indicating its botanical category. Though other red-colored beans exist (e.g., kidney beans), in Chinese, 红豆 almost always denotes the adzuki bean—not the larger, darker kidney bean (菜豆 cài dòu).

Beyond food, 红豆 carries rich cultural symbolism: in classical poetry and folklore, it represents longing and enduring love—most famously in Wang Wei’s Tang-dynasty poem 'Yearning', where 'picking red beans' evokes deep affection. Today, it appears in desserts like red bean paste (红豆沙 hóngdòu shā), soups, and health tonics, and is valued for its high protein and fiber content.