口诀 (kǒu jué) refers to a concise, often rhymed mnemonic formula used to memorize rules, procedures, or bodies of knowledge — for example, the 九九乘法口诀 (multiplication table rhyme) or traditional medical formulas. It is a common tool in Chinese folk education. The same characters also denote Kwukyel, an early Korean writing system that used Chinese characters to represent Korean sounds before Hangul was invented, but this sense is far less common and typically appears only in linguistic or historical contexts.