双曲余弦 shuāngqūyúxián hyperbolic cosine Origin Definitions Defs Strokes Stroke Words Sentences Sents 双曲 雙曲 shuāngqū hyperbolic relating to a hyperbola or hyperbolic functions余弦 餘弦 yúxián cosine a mathematical function, written as "cos", defined in a right-angled triangle as the ratio of the side adjacent to an acute angle to the hypotenuse